[Title: "Grenades sous-marines" (Depth charges)] HAS of naval parade past a naval training centre. Level shot of same, of officers taking the salute, snow on ground. Sequence on sailors being instructed on the launching of depth charges; dummy charges rolling down chute, being catapulted up into the air. Various closer shots of charges being set on launcher, trigger being pulled, charges going flying. LAS of bridge and of man in crow's nest of a submarine chaser. MS and MCS of bearded naval officer using binoculars. HAS, MLSs of stern of submarine chaser, crew releasing depth charge, charge exploding in the water.