Quarry was once a human woman named Sydney, one of several people who was kidnapped from the streets of New York by the scientists working for Oroku Saki and the Foot Clan. They were mutated in an underground laboratory in order to search for a suspected underground hideout of the Utroms. In her mutated form, Quarry had the ability to scale walls, spit corrosive acid, and also had an elongated tongue, which she used to catch little leech-like bugs out of the air to consume. While being extremely well-equipped to face any natural emergencies, she seemed to be completely terrified by the mysterious Entity in the Underground City.
She spent several weeks in captivity with the other mutants, all of whom tricked the Foot scientists into believing they had regressed into mindless beasts. Soon the creatures instigated a jail break. Though it was never shown how it happened, the creatures somehow managed to remove their shock collars and unleashed their full fury on their captors.
Despite her brutal transformation, Quarry was one of the few who still retained their human intelligence, even if she could not remember her name. The escape was bittersweet, for aside from Quarry and two other fellow mutants (Stonebiter and Razorfist), the other mutants were mentally unstable as a result of their genetic mutations, and turned on their former allies. The three mutants were able to defend themselves with a recovered energetic crystal from the catacombs and the equipment from the laboratory, which could activate a powerful force shield for the base to protect them from the others.
Through a chain of coincidences, the Turtles on a research expedition encountered Quarry and her comrades. After the Turtles learned their story, both groups allied and broke into an ancient Underground City, which had been discovered by the mutants, to acquire a new energy crystal. There they made the unpleasant acquaintance with the guardian of the city, but also found a means to transform the mutants back into their human form thanks to the radiation of the crystal moon that illuminated the city. However, the effect lasted only as long as the people were exposed to the radiation, so they were unable to leave the city.
The Turtles promised the victims that they would find a permanent cure. However, before Donatello was able to formulate a cure, the victims were so desperate that they attempted to blow off a piece of the crystal moon, but accidentally plunged sank the entire object into a lake of lava. This caused them to revert back into monsters, including Quarry.
Quarry was later returned to human from by Donatello, who had discovered that the crystals could be turned to a liquid by super sonic vibrations. He successfully injected the monstrous Quarry with the liquid, returning her permanently to human form. Sydney insisted on assisting Donatello in trying to retrieve the crystal moon from a pool of lava. They successfully returned in the Turtle Tunneler, restoring the monsters to human form with the crystal moon's light, and reenergizing the crystals. After administering the cure to her fellow former mutants, Sydney and her companions were brought back to the surface world. Her current whereabouts are unknown.
- "Notes from the Underground, Part 1"
- "Notes from the Underground, Part 2"
- "Notes from the Underground, Part 3"
- "Return to the Underground"