A wartime tribute to the men who built Canada's merchant ships during World War II and those who sailed in them. Alternating scenes in Canadian shipyards and at a merchant seamen's school show a ship taking shape as young men are trained to join its crew. When Hull 39 is launched, we follow it out to sea and hear the crew talking over their work and experiences in action.

A young doctor gets stuck on a ship after treating an injured first mate. Later, he rescues a woman from plane wreckage, and with the help of the cook, he hides her away from the rowdy and dangerous crew.

After the cultural revolution