Ralph's ex-wife Alicia cancels weekend plans with their son, Kevin, leaving him with Ralph and Pam, but then Bill shows up with an assignment for Ralph to check up on people listed as FBI security risks, leaving Kevin doubly disappointed and Pam taking up the slack. Meanwhile, Rhonda -- one of Ralph's students -- shows up and reports that her mother Rose has disappeared.
While making their rounds, Ralph and Bill investigate the disappearance of Rhonda's mother, and find that two goons had attacked her boss looking for a missing letter. He says that Rose has been doing part-time work as a file clerk at a laser technology company called Technitron, so Bill and Ralph go there and find the goons. Ralph "persuades" one of them to confess that they were hired by Technitron employee Eric Simpson, and he tells Ralph the address where Simpson is heading.
Ralph flies to the house ahead of Simpson, capturing Simpson's henchman but unwittingly allowing him to turn on a signal light to warn off Simpson upon arrival. Bill shows up a short while later, and finds a Russian signal radio. Ralph frees Rose, who tells them that Simpson is a Russian spy named Semenenko who has been stealing top secret weaponry documents from Technitron.
They track Semenenko to one of the houses on Bill's list of security risks, and tail him from there to a secret meeting by the beach, where he signals a Russian submarine with his headlights. They send some rafts ashore, where over a dozen Russian spies are waiting. Ralph disables the submarine and rounds up the spies, wrapping up the case.