A dying criminal's mind may have taken refuge in Dr. Bashir.
Kira and Bashir answer a distress call from a Kobliad ship carrying security officer Ty Kajada and her prisoner Rao Vantika, who dies after trying to escape. Kajada insists that Vantika has cheated death before and is still alive, and the crew comes to suspect that he has hidden his mind inside someone else.
Vantika, now controlling Bashir's body, works through Quark to hire mercenaries and seize a shipment of deuridium, a substance Kobliads need to survive. He takes over the freighter, but Dax disrupts his hold long enough for Bashir to lower its shields. Vantika's consciousness is driven out, and he is finally destroyed.