Jesse McCartney will play Ty, the eldest of the Locke children, which is considered the male lead on the show.
Based on the comic by Joe Hill, Locke & Key tells the story of Nina Locke (Miranda Otto) and her three children, Tyler (Jesse McCartney), Kinsey (Sarah Bolger), and Bode (Skylar Gaertner) who, after the brutal murder of Nina's husband Rendell Locke, return to Keyhouse, his old family home in Massachusetts. There, they are pestered by an evil entity that's determined to hold the family hostage one way or another until it gets what it wants.
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As Ty, Jesse McCartney will be able to show off his music talents. According to the character description, Ty was the closest with his dad and carries a special guilt for his father's death. He isolates himself a bit by retreating into his music.