Two Boy Scouts return home and explain their dishevelled appearance by describing their fire-fighting exercise.

The older boy continues to talk about scouting activities in wartime: evacuated young scouts help rural patrol collect berries for jam, fodder for animals and scrap for salvage, while older scouts help with farm work, Observers Corps and coach Home Guard in map-reading and tracking. Sea Scouts man a Thames patrol launch checking incoming ships, while town scouts paint kerbs and lamp standards for blackout, construct shelters, check gas masks.

Activities in a newly-extended Scout HQ are interrupted by an air raid, after which the returning scouts find the entire building obliterated. They resolve to build something bigger, and built to last.