Rumours spread around Poplar that a sailor with smallpox is hiding somewhere in town. Nurse Crane and Dr Turner try to track him down before he causes an outbreak. Lucille treats an expectant mother on her own, but soon feels out of her depth when she displays signs of a serious medical condition. Trixie goes to stay with her godmother, Violet and Fred organise a picnic for the parish, and Tom and Barbara return home.