For thirty years, best friends Stephanie and Philippa have been practically inseparable. There's nothing they would not do for one another. Until a few simple words change everything.

'I need you to say that I was with you.'

Steph, eternally solid, considerate and dependable, is begging her best friend to lie to the police as she's desperately trying to conceal two shocking secrets to protect her family. Pip, self-consigned to the role of scatty, frivolous hot-head is overwhelmed; she's normally the one asking for help in a crisis although never anything as catastrophic as this. Both women have always believed that friendship is built on mutual selflessness, compromise and trust. Are those beliefs now to be tested beyond endurance?