Under the direction of the genetic scientist Dr. Keppler, the Sirling Group develops a new, amphibious creature that grows at breakneck speed and reproduces itself after about a week. This creature can escape through carelessness and wreaks its bloody havoc in Lake Constance. Mark Lehmann worked on the project, but was dismissed because he did not agree that his results were being abused early on. While the corporation tries to cover up the matter and capture the beast, Mark and his wife go their own ways to render the creature harmless, but ...