Stephanie took a job at a flower shop and made a new and better life for herself when her former cohort, Martin Kettering, visited the shop. Martin attempted to blackmail Stephanie to no avail, but still wanting to keep her evil secret hidden, she lured Martin to a nearby park with a promise to pay him. The "money" actually turned out to be shredded paper, and at that moment, the evil Stephanie shot and killed Martin. She also doused Martin's body with gasoline and set him ablaze to make him unrecognizable.
However, Stephanie was pulled over for speeding as she was fleeing the scene. Even worse for the villainess, it was her third offense, so she was taken in and her car was impounded. Before her arrest, Stephanie stashed her gun inside a tuxedo bag meant for Leland Stottlemeyer, who took it to his office. To keep Leland from finding the gun, Stephanie made dastardly attempts to convince Leland's fiancee, Trudy "T.K." Jensen, to call off the wedding, including ransacking Leland's home, firebombing his car, and making a threatening phone call to T.K.
After Monk and Leland put two and two together, they confront Stephanie, who pulls out the gun from the bag and threatens Monk at gunpoint. Once T.K. arrives, Stephanie threatens her life as well, but Leland assures her that Stephanie's gun isn't loaded. Stephanie fires a shot into the air to prove otherwise, but she was actually duped into firing that shot--as it was the only one in the gun due to the magazine falling out. The now unarmed Stephanie was later arrested by Leland.
- Stephanie Briggs was the final one-shot villainess from Monk.
- Teri Polo also portrayed one-shot villainess Margaret Hallman from Criminal Minds, and later appeared as the evil Dr. Leary in 2018's Deadly Delusion.