After being shipwrecked, the Robinson family is marooned on an island inhabited only by an impressive array of wildlife. In true pioneer spirit, they quickly make themselves at home but soon face a danger even greater than nature: dastardly pirates.

Three former marines have a hard time readjusting to civilian life. Perry can't deal with the loss of the use of his legs. William is in trouble with bad debts. And Cliff can't decide what he wants to do with his life, although he gets encouragement from war widow Pat Ruscomb.