Police officer Tia recently failed her exam to become a negotiator: her dream job. But when a peaceful climate change protest at a London museum escalates, and one of the radicalised members takes Tia and others hostage, she realises this is her chance to prove she has what it takes.

Only not everyone gets out of the siege alive.

Three years later, Asher is being released from prison for the part he played at the museum that day. He's always maintained his innocence, but when someone starts threatening the survivors, leading one of them to take their own life, Tia isn't convinced Asher is telling the whole truth. Refusing to have another death on her conscience, Tia begins to investigate.