If This Is a Lie

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)

Zrinka Cvitešić

Sara

Samantha Spiro

Detective Taylor

Josef Altin

Pavel

Charlotte Rampling

Frances

David Hayman

Mr. Turner

Nicolas Chagrin

Charles

Lorraine Ashbourne

Mrs. Turner

Adrian Lester

Professor Marcus Shaw

Harriet Walter

Claire