Though Tony is happily married and John is engaged, their spouses are often bitter at them since both doctors overwork, frequently leaving home at night to attend the hospital.

After examining their remains and going through newspaper articles, Tony discovers the killer is a giant crocodile, possibly mutated by recent atomic bomb testings in the ocean.

Swearing revenge on the creature, Tony and John enlist the help of fisherman Tanaka (Manop Asavatep), who lends his boat to pursue the monster.

[4] After the crocodile demolishes a riverside village, authorities set an enormous underwater trap for it, but the plan ultimately fails.

The American Humane Association rated this film unacceptable due to a scene in which a live crocodile is slashed to death with a knife.