When several people in Los Angeles are brutally murdered with what appear to be claws, FBI agent Donna Kiel is called in by the LAPD to investigate. Since these murders coincide with Daken's arrival in L.A., she immediately suspects him to be the culprit but lacks the evidence to implicate him in the killings. When she approaches him outside the home of his lover, Marcus Roston, Daken is immediately taken by her keen intellect and straight forward attitude. When she questions him about his relationship with Marcus, he informs her that they are lovers and that Marcus is his drug dealer. He then flees from her and promises to answer all her questions if she can find him. Later, she confronts him in the back of an armored truck as he attempts to make off with millions in cash. Convinced that he is responsible for the murders she's investigating, she demands to know what motivated him to do so. Daken is unsure if he committed these crimes or not because the Heat drug that he's become addicted to causes him to black out for several hours. He then knocks her unconscious and flees from the scene.
Some time later, Agent Kiel meets with Daken at a local church at his request. He denies that he is the so called "claws killer" and offers to help her find the real killer using his underworld contacts and heightened senses. She accepts his offer because although she doesn't outwardly admit it, catching this killer has become an obsession to her. Together they examine one of the crime scenes and attend a Hollywood party in search of answers only to be confronted by Moon Knight. While Daken battles Moon Knight, Donna is confronted by a Daken doppelganger who claims to be the claws killer that she is pursuing. The impostor mocks her about details of her personal life while she chases him out of the building and on to the streets where the real Daken and Moon Knight are fighting. Unfortunately, Donna mistakes the real Daken for the imposter and shoots him in the head.
Once Donna realizes that she's made a mistake, she and Moon Knight work together to determine the real identity of the Daken doppelganger while the real Daken recuperates in a hospital. Donna returns to Marcus Roston's mansion to question him about the "heat" drug that Daken and all the claws killer"s victims have in their systems. Moon Knight discovers that Marcus is the claws killer and immediately calls Donna to warn her, but she ignores his calls. After she confronts Marcus, he attacks her and forces her to take the drug. Under the influence of the drug and at the behest of Marcus, Donna betrays Daken's location to the authorities and persuades Moon Knight to abandon his hunt for Daken. After Daken narrowly escapes the raid on his headquarters, Donna accompanies the LAPD by chopper to Catalina Island where Daken and Marcus are battling on top of a roof. Once again, Daken evades capture. Later, after Daken learns the true nature of the heat drug, he calls Donna and tells her that he needs her help. Still under Marcus' influence, she angrily rejects his offer and hangs up the phone.
Growing ill because of her addiction to Heat, Donna heads to the top of the LAPD administration building to commit suicide, but before she can jump, she is confronted by Daken. She tells him that she is tired of living with her addiction and that she wants to die, but Daken expresses how he feels a kinship with her and that if he can overcome the addiction to Heat, then so can she. After a lengthy battle in the streets of L.A., Daken and Donna are able to defeat Roston with the help of the Runaways. With Roston defeated, the two meet at a local diner to discuss how they feel about each other. Donna is suffering from many conflicting emotions about Daken; she is attracted to him, but is still appalled by his crimes and considers him a monster. Daken admits that he is a psychopath and has no sense of empathy or remorse, and tries to convince her that she is also incapable of those emotions and that the two of them are destined to be together. He takes her to an apartment building where he has imprisoned three human traffickers, then gives her a gun and tells her to free herself of inner torment by killing these men. Donna finally realizes that she is not incapable of sympathizing with others and attempts to shot Daken, realizing that his healing factor has not returned. He cuts of her hand, and demands to know why she tried to kill him. She tells him that the world would be better off without him, leaving him dejected, and the two part ways.