There has been an intruder at the Moorside Lodge mother-and-baby home, but he was scared off by Paula, who had just been looking after her baby, and nothing was taken. Allan and Hazel Mansfield have a lot of problems with their baby Peter, who needs a lot of attention. Peter is taken from his pram while Mrs. Mansfield is doing an errand at the post office. He was adopted from Moorside Lodge, and sergeant Craddock believes that his natural mother may have taken him. But time is running short, because Peter is ill and may have trouble breathing without his medicine. Greengrass has found a new way to make money: laying out driveways and such. He is helped by the mechanical wiz Gary Clarkson, who has fixed his lorry.