When the retired Major Wyatt hears that his sister Edwina's house has been burgled in broad daylight, he decides that the time has come to take action as a citizen against the rising tide of crime. Without bothering to wait for proper police help, he sets about forming his own Neighbourhood Watch.

The security marking of property plays an important part in the success of any Neighbourhood Watch scheme, yet Sgt. Springer - not known for his intuition - is more than worried by the keen enthusiasm of Wyatt and Pitt to get their hands on police engraving and marking equipment.