An anonymous tip leads to a frenzied chase -- and another puzzling clue. Zoe draws up a list of grudges. Tom glimpses a side of Rachel he never knew.

Cast: Amanda Abbington, Hannah Arterton, Tyler Conti, Paddy C. Courtney, Louis Greatorex, Michael C. Hall, Oli Meredith, Raj Paul, Joplin Sibtain, Hero Fiennes Tiffin