Grace and her dad have just moved to a tiny, sleepy Devon village, desperate to put tragic events from their old life in London behind them. But their fresh start is derailed when the second-hand Echo in their new house comes alive at midnight, and tells Grace: Grace works out it's an old recorded message, and the Echo has previously been used by four people in their village – all of whom are now dead. And Grace's passion for science and statistics comes alive. She knows within these accidental deaths, there must lie a murder – and she's going to work it out, using the methodology of a chemistry experiment. Observation; hypothesis; experimentation; results. No one believes her – except for her best friend, Maddy, who's desperate for Grace to face up to an agonising truth. And soon it's clear that whoever the murderer is, they've noticed Grace, and will do anything to keep her quiet…
