In the dynamic conclusion to last season's cliffhanger, the manhunt for Mac Taylor and the man who took him hostage continues. Additional episodes will include; guest stars, Rumer Willis, Maroon 5, Nelly and Marshall Faulk and storylines that deal with: deaths by radiation poisoning, a crime scene at 30,000 feet and the 100th episode where the team tackles their most unusual case yet, two victims, within two weeks, both named Mac Taylor. And our own Mac Taylor along with 15 others must determine the killer's motive before he strikes again.
After being taken hostage by a bank robber, Mac wakes up in the getaway car submerged in water, with a dead body in the passenger seat and no real memory of what happened. Evidence at the scene helps fill in the blanks and reveals the dead body in the car was "Joe's" partner, and "Joe" killed him while trying to find out where he hid the money from the bank. Knowing "Joe" is not going to leave without his money, the CSIs race against the clock to find him before he gets his cash and flees the country forever.
When a concert in the park turns violent and the NYPD are forced to break up the fight, a young female winds up dead in the process. As Sid is pressured to determine C.O.D., he suddenly becomes ill and has to be hospitalized. Following the incident, the CSIs learn the victim’s death was actually caused by lethal exposure to radiation, contaminating Sid in the process and forcing the lab to initiate CDC protocols. The CSIs ultimately find the source: a book from the New York City Library Antiquities Branch with pages stained by high volumes of Thallium 201, causing death by contact. The story takes yet another turn when the husband of a deceased librarian files suit against the city, believing her death was also caused by radiation poisoning. But when his story doesn’t add up, the CSI have to determine if he was the real mastermind behind the murders.
On Mac's flight to DC to testify, he winds up in a mile high crime scene when he finds an Air Marshal stabbed to death in the airplane bathroom and his gun is missing. Later, the team discovers the victim isn't an Air Marshal but rather a wanted felon who escaped custody and stole the Air Marshal's ID in an attempt to hijack the plane and flee the country. But with such a complicated plan the CSIs suspect the felon had to have an accomplice, making every passenger and crew member both witness and suspect.
A renegade street party ends abruptly when a bludgeoned woman stumbles into the midst of it and dies. Evidence reveals she was a "fixer" (a la Michael Clayton) who was entrusted with the darkest secrets of Manhattan's corporate and political elite. And when Hawkes discovers one of her clients was the wealthy benefactor who put him through medical school, he must decide whether to protect the secrets of the man who changed the course of his life, or do his job. Also, when evidence on the victim's nylons leads to a missing person, the investigation takes a U-turn into the world of "Real Dolls" -- life-sized, anatomically correct dolls -- a growing industry serving men hungry for female "companionship" without the pesky complications of a human relationship.
The murder of a real life Indian Jones leads the CSIs into the world of modern day archeologists; young, beautiful men and women who travel the world evading deadly obstacles in their search for treasures they hope will unlock mysteries of the past. As the investigation unfolds, our CSIs are shocked to learn that the life and reputation of a world-class archeologist need not be achieved through hard work and death-defying experiences. It can simply be purchased online. And buying this archeologist's adventurous life ultimately cost the victim his own. Also, the discovery of a rare and valuable Greek coin the archeologist was carrying, leads Stella down a dangerous road with the Greek Embassy and some consulate members who want the artifact.
The team investigates the murder of three co-defendants, who were out individually having some last minute fun on the eve of their trial for drug-related homicide. The likely suspect is a rival drug dealer, but unique taser burn marks on one of the victims leads Mac to an eye-witness he had made a promise to a year ago. She was a reluctant witness in the case against three dead vics, so Mac convinced her to tell him what she knew and promised he'd find evidence to keep her off the stand. But when key evidence was suppressed and the eyewitness was subpoenaed to testify, our three vics tracked her down and slashed her face as a warning to keep her mouth shut. While she has the motive, she couldn't have been at all three places at once, leading CSI to look into who sought justice on her behalf.
After finding a man bludgeoned to death in the cellar on an empty lot, the team is surprised to discover that the original crime scene is a house on a barge floating down the East River. The victim owned a house relocation company that was moving the house from Staten Island to the Upper East Side. Following autopsy, a torn card stock in the victim's hand leads the CSIs into the world of SecretsU: a website where people send homemade artistic postcards of their darkest secrets for all to see. To catch the killer the CSIs must determine if someone killed the victim to keep their secret from going public or if the victim had a secret of his own that he was killed over.
Following the murder of two people named Mac Taylor in NYC the team realizes they’re after a serial killer and our Mac Taylor could be next. But when Mac escapes a close encounter with the killer, Mac realizes the killer is only looking for one Mac Taylor and the two prior murders were mistakes of identity. After narrowing the list of Mac Taylor’s down, the potential victims are questioned endless about their lives until our team ultimately discovers the killer is after the driver of a particular car. The car he witnessed plowing over his girlfriend and speeding from the scene, leaving her to die. After finding the car in a long term garage the killer broke in and got the name of the owner: Mac Taylor. And he has been out for revenge ever since then.
Following the discovery of a skeletonized body inside the twisted metal "box" that was once a car, the CSIs must piece together the victim's shattered body to find the answers to the puzzle. After learning the victim was a missing teenager girl who ran a away from home, the case takes a turn when autopsy reveals the victim was pregnant when she was killed, and even more shocking, there’s evidence the unborn child had been removed from the victim’s womb. With no evidence that the baby is dead, the team must not only solve the murder but also rescue the victim’s missing infant from the hands of a killer. And, Danny makes his own shocking discovery: Lindsay is pregnant with his child!
As a security truck nears The Empire State Building, the security guard inside spontaneously sparks and ignites into a human torch. The CSIs quickly discern the truck was broken into, but with all the money in the vault, the team suspects it was a failed heist. When autopsy reveals the victim suffered from significant microwave burns, attention turns to the Empire State Building, known as the "Electronic Bermuda Triangle" where electronic signals are consistently jammed due to the post-9/11 communications array atop the building that produces massive amounts of microwave energy. Is it somehow possible the Empire State Building could be the highest profile murderer the city has ever known?
The CSIs appear to have an open and shut case after a murder suspect, who was caught dumping a female body, gets impaled during police pursuit. But it turns out the investigation is just beginning when the dead suspect receives a text message reading, "Is it done yet?" Autopsy on the female victim, an up-and-coming handbag designer, reveals she died from drinking sodium hydroxide, which ultimately leads the CSIs into the world of "flavor tripping parties" where partygoers eat a West African berry, known as miracle fruit, that alters taste buds and makes bitter foods taste sweet. Meanwhile, a past murder victim's daughter, Ella McBride (Ep. 507), brings Mac what could be a case breaking lead - a SecretU card with fabric from the victim's handbag line and the words, "I want her dead!" But with little evidence on the card and a variety of suspects at the party, catching the killer might take a miracle.
The CSIs investigate a woman found with a fatal stab wound after taking part in the Running of the Gowns, an annual sale where packs of young women wait in line for days to buy that “perfect dress”. The victim appears to have gotten into a fight with another woman and in the struggle a crystal from the dress sliced a major artery. Meanwhile, the CSIs are called to a second crime scene where a talented subway musician is found raped and murdered. It appears a competing performer is the killer until an odd bruise pattern on the victim connects to a wanted serial rapist. And in a strange twist the two investigations intersect when the team learns the bridal store accident vic was attacked by the serial rapist eight years ago. In order to catch the killer, the team must find the link between the two victims. Also, Hawkes reconnects with his ex-girlfriend who was attacked by the rapist years ago.
After finding various body parts scattered around the city, the CSIs discover they belong to a tough, but successful wrestling coach at a prestigious NYC High School. The case takes a dramatic turn when Mac and his team mine the coach’s computer and discover he emailed a provocative photo of a twelve-year old boy to students on his wrestling team. However, further investigation reveals that a pair of pranksters on the team pirated the coach’s Wi-Fi signal and sent the pictures from his email account in an attempt to get him fired. Unbeknownst to them, the father of one of the recipients intercepted his son’s email and took matters into his own hands. Also, Flack is dragged under a cloud of suspecion when a suspect he brings in for questioning inexplicably dies in the interrogation room.
When a father is killed while searching for his daughter who came to the U.S. with dreams of being a model, the CSIs discover his murder and her disappearance are connected to a sex trafficking ring many underage girls have falling prey to. Mac gets help on the investigation from Deputy Inspector Gillian Whitford, whose niece went missing after pursuing a misleading job opportunity in dancing. Evidence on the murdered father’s clothes leads the team to the warehouse the girls are kept in. But when they arrive to find the girls have already been moved, the team has to step up their efforts before the girls are relocated to another city or country.
When Stella attends the Deputy Mayor Stewart Kaplan’s charity gala with her firefighter escort, Brendon (from episode #503), the party is cut short after hundreds of balloons are unleashed from above, along with the body of their host. With the rank and file of the NYPD angered by the Mayor’s decision, and Kaplan’s support, of a temporary pay lag due to a budget crisis, many have a case of the “Blue Flu,” calling in sick in protest and leaving the CSIs left to pickup the slack. The investigation leads to a variety of suspects including a bitter NYPD detective, a media mogul wanting to expose Kaplan’s corrupt financial record, and Kaplan’s thirteen year old son who is suffering from a form of OCD.
When a human eyeball drops from the sky and into Stella's coffee, the CSIs find the eye belongs to a man’s body that is half buried in a balcony garden, being picked apart by talon-tagged buzzards. Suspicion falls on the victim’s wife, a Venezuela-born beauty who married the victim to obtain a green card. With the victim’s start-up tech company about to go public, his widow had everything to gain by his death. But when the widow’s brother calls 911, explaining the widow has been beaten within an inch of her life, forensic evidence tells a much more twisted story of greed and jealousy, involving the widow’s “brother” who is actually her lover.
CSI's investigate a truck bomb that explodes on a residential street in Brooklyn, which seems to be targeted at the house beside it. One young woman is found dead in the house. She turns out to be the daughter of Felix Redding, owner of the house and the intended victim. Unbeknownst to him, his daughter was making a surprise visit home from college. Analysis of the bomb connects it to an eco-terrorist group who has blown up a couple of other sites. Mac is puzzled by Redding as a target as he owns a large e-cycling business and is known as an environmentally concerned business owner. Turns out, appearances are deceiving, and Redding has been shipping e-waste to China for disposal, poisoning local villagers, instead of properly handling it and that is why he was targeted. His daughter was part of the eco-terrorist group and rented the van where the bomb was installed, however when she learned her father was the target she raced home to warn him, only to be killed herself.
Danny finally convinces Lindsay to marry him before her trip home to Montana.
Mac and Det. Flack are called to a seedy motel in Brooklyn when a woman is found shot dead in one of the rooms.
A leader of the Montiquan Indian tribe is found dead on the subway after a multi-national fight. Initially, it appears the Chief was shot but further tests reveal that he died of sepsis from an acute intestinal infection cause by a strange pick made from a Baleen whale: clearly it was not an accident. As the team searches for clues to who may have murdered him, they find a Korean father who shot his gun at his daughter’s boyfriend and the bullet pierced the subway car window. They also find a recently settled dispute between an East Indian family and the Chief as well as an angry Gaelic hurling team captain who took a swing at the Chief. None of these people killed him. Turns out one of his tribesmen did it after an online gambling operation went sour. Meanwhile, as Danny picks out boy’s names for Lindsay’s baby, he is shocked to learn they are having a girl.
While investigating the shooting of a man in an empty theater, Stella realizes that the crime scene is oddly familiar and staged.
When a man falls 52 stories to his death, and his body goes missing after it hits the ground, with no body to process, the CSIs must treat this strange development as a missing persons case.
The most exclusive jewelry auction of the year ends abruptly when an appraiser is killed during the event.
When Stella discovers that New Yorkers are being murdered over ancient Greek artifacts, she hands over her badge to follow a clue that leads to Greece and, together with Mac, she uncovers one of the greatest mysteries in history.
When transferring Robert Dunbrook's son from prison to court, the NYPD is ambushed by a group of professional kidnappers who kill a member of the team and one of the CSI's lives hangs in the balance.