If This Is a Lie

Ben Whishaw

Danny

Edward Holcroft

Alex

Jim Broadbent

Scottie

Lizzy McInnerny

Danny's Mother

David Meyer

Danny's Father

Sam Kenyon

HIV Group Chair

Deon Lee-Williams

Ryan

Louis Saint-Juste

Oldest Guy

Matthew Stagg

Young Alex

Nicola Grier

Agent in the Attic

Priyanga Burford

Clinician (uncredited)

Tobias James-Samuels

C.I.D (uncredited)

Chris Wilson

CID Officer (uncredited)