One misty morning, Liz Dunn stumbles down the road to her school and screams for help. A police psychologist gets her to reveal her story: A month earlier: three rebellious teenagers - Mike, Frankie and Geoff are trying to ditch the school field trip to Wales. The school nerd Martin helps them out by allowing them to stay in an old war bunker for the three days on the condition that his friend Liz joins them. The teens go down, party and have great fun but Martin doesn't return to let them out...

In the final days of World War II, the Nazis attempt to use black magic to aid their dying cause. The Allies raid the camp where the ceremony is taking place, but not before a demon - Hellboy - has already been conjured. Joining the Allied forces, Hellboy eventually grows to adulthood, serving the cause of good rather than evil.