The four-man crew of the RAF bomber 'B for Bertie' - George the pilot, Tom the navigator and bomber, radio operator David and Percy, the rear-gunner - have been assigned a mission to attack a power station in Hanover. On the way out, the crew evade enemy anti-aircraft fire and shake off a pursuing fighter plane by entering a cloud.

B for Bertie's arrival in Hanover is greeted by more anti-aircraft shells. But the job of finding their target is made easier by the flames left by an earlier raid - so Tom decides there's no need for a flare. Tom's first bomb falls around 100 yards short, so George goes round for another try. The second drop scores a direct hit on the storage tanks. But as George goes round for a final attempt, the plane is ripped by shells. David and Percy deal with the fire, while Tom lines up his sights and drops his final bombs. The target is completely destroyed. The crew head back, with the fire by now dealt with. Percy takes over the radio to deliver the message: 'target bombed', while David tends to his badly burned hands.

B for Bertie arrives back at base, and the crew disembark. Tom walks towards the camera and talks to the audience. What they have seen, he says, is just one sample of the thousands of missions carried out by the RAF all over the world. War savings, he explains, will help to keep these missions going and hurt Hitler's forces. He ends by urging the audience to buy war savings bonds now.