Andrews and Lahr take on an assignment for a mining company in shark-infested waters off Hawaii. The assignment: locate manganese underwater. Andrews soon learns that a cocky member of his diving team.
Shipping-company executive Robert L. Radcliffe wants Drake to retrieve an important mechanism from a sunken ship-and he hires beautiful Jill Talley to get the diver interested in the project.
Drake and Larry are hired by the U.S. Navy to retrieve the contents of space capsules launched above the ocean to test their seaworthiness. After several dry run using monkeys and crash test dummies, NASA is ready to risk the life of a real astronaut. Meanwhile, Drake has been implicated when pretty young woman is found murdered.
Over his partner's objections, Larry jumps at the opportunity to earn $400 to teach Jeremiah Wilson, an elderly man, how to safely operate his scuba equipment within 36 hours. Mike doesn't trust the man's motives and discovers his instincts are sound when he learns that his costumer is an ex-convict bent on revenge against the newspaper publisher he believes put him behind bars.
Ralph D'Amico is threatened with murder unless he continues to pay his father's blackmailer a thousand dollars a month. When he refuses to pay, two racketeers find a killer who looks exactly like Mike Madison to commit the murder so that the scuba diver will be framed for the crime.
