Nitemare 3D follows the story of Hugo, from the Hugo trilogy, a series of graphic adventure PC games consisting of Hugo's House of Horrors, Hugo II, Whodunit?, and Hugo III, Jungle of Doom!. Penelope, Hugo's girlfriend, has been kidnapped by the evil Dr. Hammerstein for use in heinous experiments. Hugo must battle through Hammerstein's bizarre mansion, underground caverns complete with prisons and laboratories, and finally through a twisted alternate dimension of demons and aliens in an attempt to save her.