Plot summary
Marcus appears to Xena as a ghost and asks for help restoring order in the Underworld. A murderer named Atyminius has stolen Hades' helmet of invisibility. Good souls have been driven into Tartarus while the wicked occupy the Elysian Fields.
Xena leaves Gabrielle beside the lake that leads below and joins Marcus. She learns that he was judged among the wicked, yet chose to seek help for the innocent rather than enjoy the disorder. When Atyminius threatens to return to the living world and resume murdering brides, Xena and Marcus escape to Hades.
Hades explains that wearing the helmet above will make Atyminius mortal again. He grants Marcus forty-eight hours of life to help Xena retrieve it. The two emerge in time to save Gabrielle from the killer, but Atyminius becomes invisible and escapes.
Xena and Marcus share a brief reunion before following him to a wedding celebration. Xena lets him overhear an apparent plan to replace the bride during a bathing ceremony, anticipating that he will choose another opportunity instead. She is waiting when he enters the bride's bedroom.
The helmet makes their fight difficult, but Xena throws a blanket over his invisible body and defeats him. She and Marcus return the helmet to Hades. Because Marcus is about to die again, Xena asks the god to judge him anew in light of his selfless actions.
This time Marcus is admitted to the Elysian Fields. Xena must leave him, but returns to the living world knowing that he has found peace and that they may one day be reunited.
Credits
Adapted from Legendary Journeys Wiki contributors, Mortal Beloved. Complete episode narrative, rewritten and condensed for clarity; causal developments and the episode's ending retained. Illustrations, dialogue quotations and non-story metadata omitted.