With danger drawing closer, Sam takes refuge in the only safe place he knows. Reed issues an ultimatum, and Helen gets one step closer to the truth.

Cast: Keira Knightley, Ben Whishaw, Sarah Lancashire, Andrew Buchan, Andrew Koji, Omari Douglas, Sam Troughton, Ella Lily Hyland, Gabrielle Creevy, Isabella Wei, Agnes O'Casey, Molly Chesworth, Paapa Essiedu, Finn Bennett, Adeel Akhtar, Tai Yin Chan, Dan Li, Charlotte Rice-Foley