The tuna clipper Star-Kist prepares to leave San Diego on a four-month voyage under skipper Joachim Qualen. Many of the crew of twelve are of Portuguese descent and have reenlisted for this trip. The engineer, radio man, bait man, cook, carpenter and net man are all willing to spend four months at sea, knowing that if the fishing is good, they should each receive approximately twenty-five hundred dollars. Also along on the voyage is Suzy, the ship's dog. After saying goodbye to their families, they leave port in late August and head for the coast of Panama, a ten day journey. Along the way, they prepare the long, bamboo poles they will use to catch the tuna. They also attempt to catch anchovetta, tuna fish bait. When sea birds alert them to the location of these fish, the crew throws out nets in a wide circle, then pulls them in. However, on this trip, the anchovetta are not plentiful and it takes several attempts to catch a sufficient amount, which they then store, live, in wells on the ship's deck. Once they locate the tuna, all of the crew, except for the skipper and engineer, move into iron racks which hang from the side of the boat and use the bamboo fishing poles, lines and hooks to pull in the tuna. Particularly heavy fish require two, sometimes three, poles used in unison. On deck, fish rain down as the men toss the lines over their shoulders and the tuna land in tanks. Suddenly, there are no more tuna to be caught in this spot and the crew has to move on. They have accumulated about a ton of tuna so far, but the boat can hold three hundred tons. The boat is then caught in a severe tropical storm during which Suzy is swept overboard and lost. The skipper decides to head for the Galapagos Islands, where they have to catch more bait. One of the crew dons a diving helmet and goes down to ensure that their nets are not destroyed by the lava rocks. However, the fishing is very poor around the Islands, and they catch barracuda and swordfish, but no tuna. Skipper Qualen then heads for the coast of Peru, where the fish are deep down in the ocean and he has to use a fathometer to locate them. The presence of hundreds of dolphins indicates that there are acres of tuna to be harvested. The fishing is excellent, with many fish weighing one hundred to three hundred and fifty pounds each. Qualen has to shoot a shark which is taking fish off the lines. Despite the bad start, the voyage is a success and with three hundred and sixty tons of tuna on board, the Star-Kist returns to San Diego for Christmas after sixteen weeks at sea. The men will spend a week at home with their families, then head out to sea once more.