Heartless Mahoney was one of Breathless Mahoney's sisters. Strongly resembling her deceased sister, Heartless held to a strict regimen of diet, exercise and cosmetic treatments that she used to maintain her youthful good looks.
Many years after her sister Breathless died, Heartless decided to seek revenge against Dick Tracy and B.O. Plenty, both of whom she blamed for her sister's downfall. She attempted to make Tess Tracy believe that Dick was having an affair, and she tricked B.O. into acting as the getaway driver in a bank robbery. Her plan was partially successful, as B.O. was arrested in connection with the crime, though Tess believed Dick when he explained how he had been set up.
In spite of her apparent success, Heartless felt unsatisfied. Tracy provided her photo to every beauty parlor, cosmetics shop and drugstore in the area, meaning that Heartless was unable to maintain her beauty treatments. Her appearance quickly deteriorated and she began to show her age. Frustrated and unhappy, Heartless left the city, sending Tracy a letter that exonerated B.O. before she left.
The Ghost of Heartless
Several years later, Heartless returned to the city, once again seeking to torment Dick Tracy. Using a series of portable optical and holographic devices, Heartless was able to create the illusion of a ghost. This specter appeared in Dick Tracy's bathroom and car, causing him to wonder if he was going insane. Running an investigation, he took a photo of the "ghost" and traced it to Heartless's town of residence, only to find that she was seemingly dead, lying in a morgue.
When Tracy returned to his city, the specter appeared again, referring to herself as "Deathless Mahoney" and blaming Tracy for the deaths of Breathless and Heartless. With Diet Smith's help, Tracy discovered the holo-projectors that were causing him to "hallucinate". Tracy went to Heartless's home, battling holographic henchmen and mind games, until he happened upon an old woman whom he quickly deduced was both Heartless and "Deathless". Since she was old and considered legally dead, Tracy gave her a one-way bus ticket to a tropical retirement, believing that she would her live out her final days in peace and seclusion.
New Allies and a New Plot
Heartless later returned again, posing as a nurse in the cosmetic surgery office of Dr. Beau Tox. Dr. Tox had provided Heartless and Prune Hilda with a treatment that restored their youthful good looks, and the three of them conspired in a revenge plot against Dick Tracy.
Their plan deteriorated, as did Prune Hilda and Heartless' faces. When the two women discovered that their faces had returned to their aged appearances, they attacked Dr. Tox with acid, attempting to disfigure him. Dr. Tox assaulted his accomplices, killing Prune Hilda.
Heartless agreed to testify against Dr. Tox (presumably in exchange for immunity or a reduced sentence), but when she took the stand her testimony was called into question because he had been disfigured, casting doubt on her ability to identify him. The charges against Dr. Tox were dismissed. Heartless' fate is unknown.
- The original Heartless Mahoney story continues the trend of associating Breathless' depiction in the 1990 Dick Tracy feature film with her appearance in the comic strip. Heartless holds a newspaper that identifies Breathless as a singer (which she was never identified as in the original story), and it was implied that some romantic attachment existed between Tracy and Breathless, despite the fact that Tracy and Breathless had very little interaction.
- Further, Heartless holds B.O. Plenty responsible for her sister's death, despite the fact that Breathless died of an illness, not from B.O.'s assault. Heartless even acknowledges late in her initial storyline that Breathless had forgiven B.O. before she died.
- The procedures that Dr. Tox performed on Prune Hilda and Heartless must have been primarily chemical and therapeutic in nature, as an actual surgical procedure would not have "worn off" like theirs did.
- In 2003, Dr. Tox described one of his nurses as being "only 72 years old". Ambiguity in the artwork makes it unclear if her was referring to Prune Hilda or Heartless. There are arguments that can be made in favor of both women, though in both cases it contradicts the sliding time-line of the strip.