An explosion at the docks badly affects the husband of a new mother, Patsy feels under pressure, and Sister Ursula continues to test the patience of everyone at Nonnatus House.
Nonnatus House welcomes a new recruit, Fred and Violet take in a vulnerable young man, Sister Monica Joan makes a discovery, and Trixie meets a charming dentist.
As the Cuban Missile Crisis brings fear to Poplar, Sister Julienne tries to arrange the return of Sister Mary Cynthia, while Valerie deals with a very challenging case.
The effects of thalidomide continue to take their toll on a former patient, leaving Patrick guilt-ridden, while a shocking incident leaves Phyllis consumed with guilt of her own.