A meeting in a London bus with jewel thief Lady Christina takes a turn for the worst for the Doctor when the bus takes a detour to a desert-like planet, where the deadly Swarm awaits.
The lives of six girls belong to different worlds although connected to each other through a doll called Molly, whose existence dates back to 1976, when she appeared among the rubble of the great fire of the San Carlos orphanage, in northern Spain.