This was meant to be the perfect trip. The Northern Lights. A luxury press launch on a boutique cruise ship. A chance for travel journalist Lo Blacklock to recover from a traumatic break-in that has left her on the verge of collapse, and to work out what she wants from her relationship. Except things don't go as planned.

Four friends. One promise. But someone isn't telling the truth. The twisting new mystery from bestselling phenomenon Ruth Ware. The text message arrives in the small hours of the night. It's just three words: I need you. Isa drops everything, takes her baby daughter and heads straight to Salten.