David Tennant as RD Laing

Elisabeth Moss as Angie Wood

Michael Gambon as Sidney Kotok

Gabriel Byrne as Jim

David Bamber as John Meredith

Olivia Poulet as Maria

Adam Paul Harvey as Paul Zemmell

Jerome Holder as John Holding

Linda Hargreaves as Mrs Holding

Declan Wilson as Mr Holding

Lucie Glynn as Joan Walker

Cia Allan as Mrs Walker

Trevor White as Bryan

Rebecca Gethings as Jane Simons

Lydia Orange as Sarah

Tom Richards as Raymond

James Utechin as Sam

Alexandra Finnie as Susie Laing

Ruby Winter as Karen Laing

Alistair Stoddart as Laing Child

Jake Saville as Laing Child

Amelia Leather as Laing Child

Isaac Benn as RD Laing as a Child

Nigel Barber as Dr Bloom

Paul Hunter as Glasgow Consultant

Bryan Bounds as Radio Host

Matthew Jure as Richard Long

Kelby Keenan as Olivia Keenan

Alex Walton as Sean

Zara Plessard as TV Presenter

Aaron Taylor as Pieter Kotok

Caitlin Innes Edwards as Mrs Kotok

Leo Heller as Young Sidney

Richard Calder as Chairman / Psychiatrist

Philip Gascoyne as Psychiatrist

Victor Ptak as Psychiatrist

Stephen Schreiber as Psychiatrist

David Annen as Psychiatrist

Helen Belbin as Amelia Laing

Peter F. Gardiner as David Laing

Wendy Barrett as Anne Laing

Alastair Natkiel as Guest at Jazz Club

Maya Chesca Miles as Fran Klein

Lanna Joffrey as Eleanor Goodhart

Sam Booth as Michael Lear

Nicola Simonds as Kingsley Hall Guest

Judith Alexander as Social Worker

Striker John as Policeman

Michael Smoker as Policeman

Jeannie McGinnis as Airport Check-in Woman

Jamie Edgerton as Barman

Mike Shoring as Tai Chi Instructor

Redford Glynn as Baby Gabriel