On day one, an off duty police officer named Laurie Franklin (Suranne Jones), is on a train accompanying her mother Jen (Anne Reid), who suffers from dementia, to hospital. The train suddenly comes to a halt, and it soon transpires that a young Muslim woman has jumped from a bridge, hitting the train, leaving the train driver, Pat (Steve Evets), traumatised. Laurie and conductor Danny (Matthew McNulty) take charge until the railway police arrive. Danny gives Jen and Laurie a lift to the hospital, where Jen fits and is admitted overnight. At the hospital, Laurie learns from social worker Colly (Nina Sosanya) and foster father Nick (Derek Riddell) that a baby has been abandoned in a toilet and found by cleaner Didi (Cornell John). The baby is named Michael, after Didi's brother. As Danny and his Muslim wife Nusrat (Shivani Ghai) discuss adoption, Laurie believes that the baby and the suicide are connected. DI Mal Craig (David Morrissey), the Railway Police inspector, tells her that the corpse is in fact that of a young man, not a woman as had been previously thought.