The Salisbury Poisonings

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

They are taken to hospital, where doctors struggle to diagnose the source of their illness. DS Nick Bailey decides to investigate the Skripals' home, but soon after returning to work he begins to feel ill.

Tracy Daszkiewicz, Director of Public Health for Wiltshire Council, is called into an emergency meeting, where it's revealed that it was an attempted assassination with an unidentified poison. Tracy realises the potential danger and locks down the main sites but, when CCTV footage shows the Skripals have been all over town, she fears the entire city centre could have been infected with an unidentified toxin.

Meanwhile, Dawn Sturgess is furious at herself for missing a planned trip to the playground with her daughter. As her boyfriend, Charlie Rowley, comforts her, she vows to turn things around.

As Tracy struggles to deal with the responsibility of having the safety of thousands in her hands, Nick's condition worsens.

Continuing to fight for the resources necessary to contain the contamination, and realising the scale of the task ahead, Tracy needs to move out of her family home and into her office, to the dismay of her husband and son.

As Nick fights for his life, his wife Sarah is beside herself with worry, but tries to remain calm for their daughters.

As the decontamination efforts continue, Charlie, who lives in temporary accommodation, is delighted to discover he's been given his own flat. Dawn is thrilled for him.

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.

Dawn is staying with Charlie, who surprises her with some perfume.

She sprays herself but, within minutes, collapses. She is admitted to hospital with a suspected drug overdose. Charlie collapses a few hours later and joins her. Dawn's family rushes to her bedside and are stunned to learn she has been contaminated with Novichok.

Nick, keen to get back to work, but still struggling to deal with the trauma of what he went through, is floored when he hears about Charlie and Dawn.

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.