He intends to extort $500,000 ransom by threatening to blow up a crowded airline using an explosive device that electronics expert Jim Molner has unwittingly designed for him.

Hoplin calls giant 20th Century Airlines and tells them there is a bomb aboard one of their flights, then he and his gang take Molner, wife Joan and young daughter Patty hostage.

The plane lands safely and a bomb squad finds and disarms the powerful miniature device - just as intended, as Hoplin was only using the incident as proof of his ability to plant one anywhere without prior detection.

Joan is forced to go alone to collect the ransom, while two of Hoplin's accomplices, a beautiful but hardened young mistress, Kelly, and yes-man Vince, guard her husband and child in a mid-town penthouse apartment.

For this strictly-for-kicks melodrama, which Andrew and Virginia Stone have made on an undisguised low budget for Metro-Goldwyn-Mayer, is full of the sort of fast arm-twisting and menacing of innocent people with senseless perils that passes for ruthless realism among those patrons who don't like to use their heads.

:"Director-writer Andrew L. Stone presents an ill-conceived attempt at making a realistic thriller about a mad bomber extorting money in a terrorist plot via the 1950s.

There are too many implausible occurrences for the narrative to handle and it all falls by the tracks in the climactic hysterical underground subway chase scene, which yields to Hollywood melodrama ...