Tim Avery, an aspiring cartoonist, finds himself in a predicament when his dog stumbles upon the mask of Loki. Then after conceiving an infant son "born of the mask", he discovers just how looney child raising can be.

When timid bank clerk Stanley Ipkiss discovers a magical mask containing the spirit of the Norse god Loki, his entire life changes. While wearing the mask, Ipkiss becomes a supernatural playboy exuding charm and confidence which allows him to catch the eye of local nightclub singer Tina Carlyle. Unfortunately, under the mask's influence, Ipkiss also robs a bank, which angers junior crime lord Dorian Tyrell, whose goons get blamed for the heist.