Molly Walker first appeared in "Don't Look Back". Sylar had killed her parents, and she was hiding under the stairs. She was found by Matt Parkman who found her using his new found of ability of telepathy. Next, Sylar tried to kidnap her while she was being kept in a police station. She was rescued by Matt and Audrey.
She next appeared in the custody of the Company. She had been infected with the "Shanti virus" but she was cured by Mohinder Suresh. We also dicover in that episode that she has the ability to find anyone, the power of Clairvoyance.
In the final episode, Molly reveals that she has a "boogeyman" who can see her when she looks for people.
In season 2, Molly and Mohinder is in the care of Mohinder and Matt. Molly has constant nightmares about the "boogeyman" and draws disturbing pictures in school. When Matt asks her to find his father, she is scared, revealing that he is her "boogeyman". She finds Maury Parkman in Philidelphia, but he sees her, and puts her into a coma. Mohinder takes her into The Company, where she lays in a coma, until Matt traps his father and escapes with Molly.
Sylar and Maya then babysit Molly, in an attempt to get him to help them. Sylar pulls a gun on all of them, and Mohinder takes them all to his new lab, Issac's loft. Molly offers to find Alejandro for Maya, but she is unable to find him, meaning he's dead. Luckily, Elle Bishop later arrives and attacks Sylar, making him flee. Mohinder says it was good that Elle turned up, because Sylar probably would have killed them all otherwise.
Molly describes her power as the ability to "find people". By thinking of someone, Molly can psychically determine their exact location fairly quickly and can point out their location on a map. She also receives psychic visions of the person's surroundings. The full extent of her power and what it can locate, beyond people, has not been revealed; Adair Tishler stated in an interview with Entertainment Weekly that Molly's ability is to "find anyone or anything".Those with telepathic powers, namely Maury Parkman, can detect and resist her attempts to locate them. Maury, dubbed the "Nightmare Man" by Molly because of this, can even affect Molly's mind if she attempts to track him. As seen in "Powerless", she can only find people who are alive, as she unsuccessfully tries to find Maya's dead brother.
- Molly is referenced in the Heroes 360 experience in an email from the future Hiro Nakamura, in which he says he has found Molly Walker and is searching for "others" like her.
- In an alternate future of "Five Years Gone", Molly is mentioned to be under Mr. Bennet's care. She may have been killed by Sylar since the other people Noah mentioned were.
- In an alternate future of "I Am Become Death", Molly is living with Matt and his wife Daphne. She uses her power to locate the younger Peter Petrelli.