Carlo Roma and his foster-son, Toma, and their friend Beppo, are living a happy fisherman's life in San Francisco until Carlo's widowed sister-in-law, Stella, shows up with her brat-son, Rudolph, and takes over. Poor Toma gets his feelings hurt and the idea he "isn't wanted" and runs away

After being nabbed while trying to stow away on board an ocean liner en route to Hawaii, young Bobby Breen sings for his travel fare and, along with sidekick Pua, turns detective to recover stolen naval documents from crooks