HBO Max's thriller The Flight Attendant has brought another castmember on board.

Grey's Anatomy and Genius veteran T.R. Knight has joined the Kaley Cuoco-led series as a regular. He will be part of a cast that also includes Sonoya Mizuno, Michiel Huisman, Colin Woodell and Griffin Matthews.

Based on a novel by Chris Bohjalian, The Flight Attendant stars Cuoco as the title character, Cassie, a woman who wakes up in the wrong hotel, in the wrong bed, with a dead man — and no memory of what happened. Cuoco is also an executive producer on the project via her Yes, Norman banner.

Knight will play Davey, Cassie's older brother, who gently disagrees with her life choices and is constantly frustrated that his sister remembers their childhood very differently than he does.

Following a five-season run on Grey's Anatomy, Knight appeared in both seasons of National Geographic's anthology Genius, playing J. Edgar Hoover on Einstein and Max Jacob on Picasso. He also leads the voice cast on Hulu's kids series The Bravest Knight. Other credits include 11.22.63, The Good Wife and The Catch. Knight is repped by SDB Partners and Paul Hastings LLP.

The Flight Attendant comes from Warner Bros. TV and writer and showrunner Steve Yockey. He executive produces with Cuoco, co-showrunners Meredith Lavender and Marcie Ulin, prolific producers Greg Berlanti and Sarah Schechter of Berlanti Productions and Susanna Fogel (The Spy Who Dumped Me), who is directing the first two episodes. Yes, Norman's Suzanne McCormack is a co-EP.

The Flight Attendant is one of more than 20 original series in the works at HBO Max, the WarnerMedia streaming platform that is set to launch in May. Other series on tap for the service include a Gossip Girl update, the comedic anthology Love Life, the Ridley Scott sci-fi drama Raised by Wolves (which was initially set for TNT) and a Green Lantern series, also from Berlanti.