4 March 2018. Emergency services descend on Salisbury's city centre where they find Sergei and Yulia Skripal unconscious on a park bench. ...

Several months later, Charlie fatefully rummages through a charity bin and finds what looks like a perfume bottle - but is actually a container full of Novichok. ...

Tracy, whose life had just begun to revert to normal, is devastated, and the team race to work out what has been missed, and how to make Salisbury safe again. ...