Helen and Cleet decide to take a boat trip up the St Johns River to Jacksonville so that they can spend their last day together before Cleet has to return to the University. They are unaware that the Gill Man is following them. When they reach Jacksonville, they go dining and dancing at the Lobster House, situated on a pier beside the river. As they're enjoying the jazz band, Gill Man bursts into the restaurant, grabs Helen, and carries her into the water. Helen tries to escape by climbing onto a marker buoy, but the creature pulls her back into the water. Cleet swims out to the buoy, but Helen is no longer there. The police have been alerted, and they begin combing the area. Two men find Helen lying on the beach at Point Diego, but before they can alert anyone, the Gill Man attacks them and carries Helen off again. When they find the bodies of the two men, the police concentrate their search around the Point Diego area. They find Helen lying on the beach, having been deposited there by the creature so that he could return to the water to get back his strength. Unfortunately, the Gill Man returns, picks up Helen, and starts carrying her back into the water. Having been alerted by a flare, Cleet arrives. He runs toward the creature, yelling, Stop! Stop!' The creature puts down Helen, and the police open fire on him. In the final scene, as Helen and Cleet hug each other, the Gill Man can be seen floating lifelessly.