A rash of petty crimes are being committed by the city's most prominent citizens. Local authorities are baffled by the case. When arrests have been made, these well-to-do criminals seem entranced, muttering one phrase over and over-"I'm dead! Thanatos killed me!" After a brief visit with friends in the city, Aquaman races back to the sea, to replenish his strength and vitality. En route, Aquaman is attacked by a quartet of hoodlums. Too long out of water, Aquaman is weakened enough for the hoods to get the best of him. Inexplicably, Aquaman finds himself standing outside of an old, crumbling manor house. A note from his wife, Queen Mera of Atlantis, seems to have lead him here. Aquaman's reflection, in a mirror at the top of some stairs, twists and distorts into a misshapen, brutish version of the Sea King. Astonishingly, the monstrous reflection comes to life and bursts out of the mirror. Taken by surprise, Aquaman is quickly beaten down, the sounds of laughter ringing in his ears, as he slips into unconsciousness. Upon awakening, Aquaman finds himself back in Atlantis. Apparently, surface dwellers returned the King of the Seas to the ocean, and soon after, Aquaman was brought back to Atlantis. Mera denies ever leaving Aquaman any kind of note. Aquaman realizes that he was lured to the old house, specifically to release the creature imprisoned in the mirror. He is about to set off in pursuit of the brute when he is suddenly overwhelmed by a wave of dizziness.
Back on dry land, the creature, calling itself "Thanatos", finds itself growing weaker. It feels a strong compulsion to head for the ocean. Entering the sea, Thantos finds his strength and vitality returning to him. On instinct, Thanatos travels to Atlantis, then attacks the city guards. Drawn in by the sounds of conflict, at the city gate, Aquaman confronts Thanatos. Once again, Aquaman's bestial doppelganger defeats him in combat, raining blow after blow down on the Sea King, until Aquaman collapses. Awakening again in his royal bedchambers, Aquaman is informed by Mera that Thanatos has left Atlantis. In the city, police scientists have determined that the well-to-do criminals have, in fact, been brainwashed. The conditioning process finds each victim confronting their own evil side, manifesting itself as "Thanatos". Once "killed" by "Thanatos", the subject's mind becomes awash in immorality, leading to their crime sprees. Determining that "Mr. Big", the syndicate leader who once kidnapped Queen Mera, has to be profiting from this scheme, the officers decide to pay him a visit. Meanwhile, Aquaman's hunt for Thanatos has lead him to the undersea, "Old West" town of Rusdic. Aquaman takes respite in the town's saloon, but departs when he is denied service. Outside the saloon, Thanatos is waiting for Aquaman. A local gives Aquaman a spear gun. Aquaman and Thanatos face off against each other in the street. A wave of dizziness washes over Aquaman, just as Thanatos shoots him.
Aquaman awakens, yet again, in his royal bedchambers. Aquaman is confused and begins to suspect that all is not what it seems. Before he can dwell on the situation for long, Thanatos punches through the wall. This time, he means to kill Aquaman. Arriving at an abandoned warehouse, local authorities storm the hidden lair of the syndicate leader. There, within the warehouse, the police discover more innocent victims being transformed into criminals, by the syndicate's machines, including Aquaman. His entire conflict with Thanatos has, essentially, been fought in dreams. Due to Aquaman's indomitable will, the syndicate's machines have been unable to recondition the Sea King's mind. A violent confrontation breaks out between the syndicate men and the police. At that same moment, Aquaman is battling Thanatos, for his very will. Though he is outmatched physically, Aquaman's greater speed and fighting prowess win the day. The police take down the syndicate, and release the prisoners. It's too late for the wealthy citizens. Their minds have been completely reconditioned. Aquaman, however, recovers. Aquaman returns to Atlantis, this time for real.