On the shores of Lake Michigan, an eccentric sea captain named Seafield embarks on a mission to avenge his father's death, which he claims was caused by a mysterious monster lurking in the depths. Driven by a mix of bravado and absurdity, Seafield assembles a misfit team of specialists: a weapons expert named Sean Shaughnessy, sonar technician Nedge Pepsi, and former N.A.V.Y. sonar officer Dick Flynn. Each member brings unique, albeit questionable, skills to the mission. The team members are not entirely convinced of Seafield's tales but agree to help in the hunt for the illusive creature.

As they venture into the lake, their attempts to locate and confront the monster lead them through a series of increasingly bizarre and comedic mishaps. The group's various plans—from using cutting-edge sonar technology to setting elaborate traps—seem to do little more than showcase their collective ineptitude. Amidst their chaotic efforts, tensions rise and personal agendas start surfacing. As the group teeters on the edge of falling apart, Seafield's obsession grows stronger, pushing them all into a final, unpredictable confrontation with the dark forces beneath the water.