Three young cousins and their companions confront sudden financial reverses and set out to restore their family's fortunes through business ventures and adventurous outings. Their efforts lead to campus pranks, mysterious disappearances, criminal plots including a daring hold-up, investigations that uncover hidden evidence, and a perilous sea voyage beset by storm and explosion. Along the way they encounter unexpected allies, solve puzzles linking scattered clues, and face moral tests of loyalty and perseverance. The narrative combines episodic scenes of suspense, outdoor adventure, and detective work, culminating in revelations that resolve the family's troubles and bring the group safely home.