Xena: Warrior Princess - Season 1 Episode 16 -

Xena's dead love Marcus appears on earth to tell her the underworld has been taken over by mad Atyminius, who has confined the good souls to Tartarus and given evil the run of the Elysian Fields. But if Xena succeeds in getting Hades' Helmet of Invisibility back, Marcus will be punished in Tartarus forever.