Zac Efron as Richard Samuels

Christian McKay as Orson Welles

Claire Danes as Sonja Jones

Ben Chaplin as George Coulouris

Zoe Kazan as Gretta Alder

Eddie Marsan as John Houseman

Kelly Reilly as Muriel Brassler

James Tupper as Joseph Cotten

Leo Bill as Norman Lloyd

Patrick Kennedy as Grover Burgess

Aidan McArdle as Martin Gabel

Al Weaver as Sam Leve

Thomas Arnold as George Duthie

Megan Maczko as Evelyn Allen

Jo McInnes as Jeannie Rosenthal

Iain McKee as Vakhtangov

Simon Nehan as Joe Holland

Travis Oliver as John Hoyt

Simon Lee Phillips as Walter Ash

Daniel Tuite as William Mowry

Imogen Poots as Lorelei Lathrop

Saskia Reeves as Barbara Luddy

Shane James Bordas as Conspirator

Alessandro Giuggioli as Conspirator

Harry Macqueen as Conspirator

Rhodri Orders as Conspirator

Michael J. McEvoy as Epstein

Garrick Hagon as Dr. Mewling

Aaron Brown as Longchamps Kid #1

Emily Allen as Virginia Welles

David Garbutt as Mercury French Horn Player

Jay Irving as Mercury Percussion Player

Steven Parry as Mercury Trumpet Player

Marlene Sidaway as Grandmother Samuels

Robert Wilfort as Radio Director

Michael Brandon as Les Tremayne

Nathan Osgood as Radio Announcer

Janie Dee as Mrs. Samuels

Eddi Reader as Singer

Jools Holland as Band Leader

Gilson Lavis as Drummer

Dave Swift as Double Bass

Mark Flanagan as Guitar

Fayyaz Virji as Trombone

Michael Rose as Tenor Sax

Phil Veacock as Alto Sax & Clarinet

Nick Lunt as Baritone Sax

Jason McDermid as Trumpet

John Young as Longchamps Kid #2

Greg Bennett as Hobo

Cris Blanco as Museum Patron (uncredited)

Lexie Lambert as Lizzy (uncredited)

John Patten as Theatre Owner (uncredited)

Chris Wilson as Studion Foley Artist (uncredited)