Farnsworth is mourning the loss of his first Planet Express Crew, having it been exactly 50 years since they were lost with Dr. Zoidberg as the only survivor of the incident. To commemorate the anniversary, Farnsworth orders the current crew to pick up a memorial and fly it back to Earth. However, on the way back, there is the Bermuda Tetrahedron, which is thought to have killed the lives of many spaceships which have travelled through it. But Leela insists that they should fly through anyway.
In the spaceship graveyard inside the Bermuda Tetrahedron, the crew spots the old Planet Express Ship, where they find the crew to have been gone. However, inside the old ship, the crew is attacked by a four dimensional space whale (which Leela refers to as a 'Möbius Dick'), and they flee to their current ship. The whale re-attacks them, eating their monument and engine, but leaves the ship afloat.
Leela orders the crew to set the sun-wave sails to replace the spaceship engine. But instead of fleeing the Bermuda Tetrahedron and telling Farnsworth what went wrong, Leela decides to hunt down the whale and does not listen to any of her crewmate's warnings. Her obsession with killing it, eventually means the crew with the exception of Zoidberg, who went back to Farnsworth in an escape pod to tell him what happened, is eaten by the whale, wherein the whale consumes her, as it feasts on obsession. But Leela manages to get the whale back to Earth, where she can re-introduce the crew and the first crew to their relatives.