When an explosion rips through the chemistry lab at Raven's Hill School and six girls are injured, the first thought is that it's an experiment gone wrong. Then the guards start investigating and suspect a bomb. But if so, who was it targeting – and why? Could toxic relationships have bubbled over into violence?

The injured Frankie and Sorcha team up with Jess to try to find out what actually happened. But what they discover is far more sinister than even they could have imagined …