N has been a day patient at north London's Dorothy Fish day hospital for 13 years - her ambition is never to leave. Then she meets glamourous new patient Poppy Shakespeare, an ad agency receptionist convinced she's not mad.

Naomie Harris
as Poppy

Anna Maxwell Martin
as N

Tessa Peake-Jones
as Rhona

Claire Benedict
as Rosetta

Adrian Scarborough
as Middle Class Michael

Cathy Murphy
as Astrid

Kolade Agboke
as Wesley

Marie Critchley
as Tina

Bruce MacLeod
as Brian the Butcher

Penny Layden
as Sue