Captain Nemo was a character in the novel 20,000 Leagues Under the Sea. His ghost attacked a delicatessen that was named after him(Ray commented that the owners should have asked Captain Nemo for permission to use his name). The Ghostbusters then trap him, but four time-travelers named Turek, Cowan, Gard, and Bethany steal the trap and keep it with them and teleport all of the Ghostbusters to four alternate realities. It turns out that the four time-travelers stole the trap because they needed Captain Nemo to tell them the location of his submarine the Nautilus. The Nautilus happened to have a power source that the quartet wanted to use to create a powerful weapon. Nemo was then freed and helped the Ghostbusters and The Slug defeat the four felons. Nemo and the Slug then go back to the future using the Nautilus.
Captain Nemo can conjure up minions resembling anthropomorphic sea animals. However, his minions are extremely vulnerable to proton streams and they can cease to exist if Nemo is captured in a ghost trap.