A massive earthquake shakes up the southland. Cort and Craig go diving and when they return to the boat, they discover that two fishermen on another boat are dead. Then Cort smells poisonous gas and they swim away from the boat. When there's an aftershock, they get trapped inside a cave. Mitch and Garner locate them from a helicopter and Mitch has to use dynamite to get them out.
This long-running series follows the adventures of a team of lifeguards on the crowded beaches of Los Angeles County. Veteran lifeguard Mitch Buchannon watches over the younger lifeguards that come and go with each passing season as they keep the beaches safe for vacationers. Frequently he must take action to save them from the raging seas and from the raging tempers that sometimes flare up between the young guards in this stressful job.