Laurie, a divorced policewoman,is on a train with her mother Jen,going to hospital for Jen,who has borderline Alzheimer's,to be assessed when the train grinds to a halt. A young Muslim woman has jumped from a bridge under its wheels. With Pat,the driver,traumatised,Laurie and conductor Danny take charge until the Railway Police arrive. Danny gives Jen and Laurie a lift to the hospital,where Jen fits and is admitted overnight. Here Laurie learns from social worker Colly and foster father Nick that a baby has been abandoned in a toilet and found by cleaner Didi,who swears to protect it and after whose brother Michael the baby is named. As Danny and his Muslim wife Nuss discuss adoption Laurie believes that the baby and the suicide are connected. Mal Craig, the Railway Police inspector, tells her that the corpse is that of a youth and not a woman.