When a baby is born with severe deformities of the kind later identified as caused by the drug thalidomide, the midwives find it difficult to handle the situation, and the baby's father rejects her completely, to his wife's dismay. Trixie's new sideline as a keep fit instructor brings her into conflict with Sister Julienne, and she also becomes suspicious of the relationship between Barbara and Tom. Rather than return to Wales as her mother wishes, Delia moves into Nonnatus House.

Dr Turner is horrified to realise he may be partly to blame as the cause of the recent rise in birth deformities comes to light, and tries to prevent further cases. Sister Evangelina returns to work, but has clearly been affected badly by her stroke, and her health continues to deteriorate. A pregnant bride goes into labour during her wedding reception, while her mother is forced to come to terms with her grandchild being conceived out of wedlock.

Dr Turner helps the Mullucks cope with the stresses of caring for a disabled child as the terrible legacy of thalidomide becomes apparent and Nurse Crane faces an unexpected crisis.

The Turners support a family still suffering the devastating effects of thalidomide, Miss Higgins is involved in an unexpected delivery, and the community stages a talent show.