It's 1944 and occult leader Grigori Rasputin (KAREL RODEN) and his German assistants Kroenen (LADISLAV BERAN) and Ilsa (BRIDGET HODSON) are trying to bridge a portal into the supernatural world so that the Nazis can win WWII. The Allied forces kill Grigori and stop the effort, but not before a small, devilish creature crosses over.
Adopted by Professor Trevor "Broom" Bruttenholm (JOHN HURT) and raised as his son, Hellboy (RON PERLMAN) now lives at the Bureau of Paranormal Research and Defense, a covert branch of the FBI. With devilish horns (that he keeps filed down) and tail, and a gargantuan concrete-like fist, Hellboy has a reputation for getting the job done when it comes to taking care of monsters and other such supernatural problems.
He's also known for his solitary and caustic attitude that had led FBI rookie John Myers (RUPERT EVANS) to be named as his new nanny, keeper and best friend. Arriving at the BPR&D, John not only meets Broom and Hellboy, but also Abe Sapien (DOUG JONES), a psychic fish-man, and later
Liz Sherman (SELMA BLAIR), a troubled fire starter.
Hellboy is sweet on her and thus grows jealous when she seems to take a liking to John. Yet, he doesn't have much time to dwell on that. It seems that the immortal Ilsa and Kroenen have resurrected Grigori from the dead and now wish to complete their supernatural takeover of the world.
With Head of Special Operations agent Tom Manning (JEFFREY TAMBOR) growingly increasingly perturbed with the mutants and their antics, Hellboy and the others pay him little heed as they set out to find and stop Grigori and the others before it's too late.