This is a story of two Lucys – a police detective who failed to stop a tragedy, and a mother who may have to sacrifice everything in order to fulfil promises made in a previous life. Their realities collide in a mission to stop the worst thing imaginable. But who can you trust when your memories are no longer your own?

• Jessica Raine
• Peter Capaldi
• Nikesh Patel
• Phil Dunster
• Benjamin Chivers
• Talia Walker Bassols
• Rhiannon Harper-Rafferty