Ash and Machin are recalled to London from a bomb disposal course and attend to a bomb in a school yard that is dangerously close to a telephone exchange. When another bomb is uncovered close by, Ash reluctantly allows Machin to defuse the his first bomb.

Ash and Susan go off for a quiet weekend away but Ash is recalled to deal with an unexploded bomb and Susan returns home to find her husband waiting for her.

The Germans have been dropping a new butterfly bomb that are proving difficult to defuse. 347 Section is one of a number of units called to a small English village to deal with them.