Warner Bros.' highly-anticipated adaptation of The Goldfinch has picked up another important cast member, with IT and Stranger Things star Finn Wolfhard joining the cast. The young actor will portray the younger version of the pivotal Boris character, with the adult version being played by Aneurin Barnard (Dunkirk). Young Boris makes quite an impact on the life of the lead character Theo Decker, although it hasn't been revealed who will play the young Theo quite yet.

In the original Pulitzer Prize winning book by Donna Tartt, the story follows 13-year-old Theo Decker, who was visiting the New York Metropolitan Museum of Art with his mother, to see an exhibition of Dutch masterpieces, which includes Carel Fabritius's The Goldfinch. Theo's life is upended when a bomb explodes in the museum as part of a deadly terrorist attack that kills his mother and several others. Amid the confusion, Theo comes across an old man in the rubble, who gives him a ring and a strange message and points to what Theo thinks is The Goldfinch painting, which he steals before making his escape.

Theo meets young Boris in Las Vegas, after his deadbeat father finds him living with the Barbours following his mother's death, and takes him to Sin City. Boris is the cosmopolitan son of a Ukraine emigre, and they both share a bond since their mothers have died, and their fathers are both essentially absentee parents. Boris first introduces Theo to drugs and alcohol. The story follows Theo through his various adventures in New York, Las Vegas and beyond, as he gets sucked into crime and deceit within the underground art world. There are still a number of key characters left to cast, although many roles have been filled already.

Related: The Goldfinch Brings on Tinker, Tailor, Soldier, Spy Writer

The cast also includes Luke Wilson as Larry Decker, Theo's father, Sarah Paulson as Xandra, the girlfriend of Theo's father, Willa Fitzgerald as Kitsey, the youngest of the Barbour children, Luke Kleintank as Platt Barbour, the oldest child, Ashleigh Cummings as Pippa, the redhead Theo falls in love with, and Jeffrey Wright as Hobie, Theo's mentor. Other pivotal roles that have yet to be cast are the Barbour parents, Theo's school friend Andy Barbour and Welton "Welty" Blackwell, the old man 13-year-old Theo meets in the rubble, who was Hobie's old business partner.

Warner Bros. had picked up the rights to The Goldfinch in July 2014, with the 784-page novel originally being eyed as a mini-series before it was adapted into a feature film. John Crowley (Brooklyn) has been set to direct The Goldfinch from a screenplay by Peter Straughan (Tinker, Tailor, Soldier, Spy), with Nina Jacobson and Brad Simpson producing. The Hollywood Reporter reveals that prodution is scheduled to begin later this month, so we should have more casting updates soon.