Ash is ordered to take a defused bomb direct to a scientist working on ways to get around the booby-trap timer.

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.

Newly-promoted Major Francis takes command of the unit and proceeds to enforce new disciplines, but his chief target seems to be Ash and his men.

347 Section cooperates with the Royal Navy to deal with a bomb that has a 17-second fuse. Ash decides to ask Susan to marry him.

Ash is assigned to Cambridge to help Dr. Gillespie with the new Y fuse, and meets Susan again.

Ash convalesces after a near-fatal accident while defusing a mine. With his mobility severely impaired, he is to be reassigned to light duties away from the bomb disposal unit.