Young recruit Brian Ash is shocked to learn that the 97th Tunnelling Company of the Royal Engineers is actually a bomb disposal squad.

Brian's recklessness with a bomb lodged within a burning building nearly costs him and a fellow officer their lives.

After attending a bomb disposal course, Brian and Ken Machin are sent to defuse a German bomb, but their scant knowledge proves inadequate.

Tragedy results when Brian and the men of 347 Section are ordered to risk their lives to test a new, unproven device on a live bomb.

Brian must defuse an especially dangerous bomb designed to thwart disposal attempts; Susan asks Brian to meet her in London for a date.

Susan connives to meet Brian on his weekend off, but her husband's unexpected return and her father's suspicions cut their visit short.