Tanner is a recovering alcoholic who met Lianne Mars during rehab. The two formed a bond and eventually got married, soon afterward conceiving Hunter. While Tanner had heard about Veronica, Veronica had no idea that her mother had recovered, married, or had any more children. They first meet after Aurora's disappearance. While Tanner seems nice enough, Veronica continually notes how he sets off her "bullshit meter".
In the end, Veronica discovers that Tanner was forced by his associate, Duane Shepard (alias Lee Jackson), to capitalize upon the disappearance of Hayley Dewalt by faking his daughter's abduction. Their plan was to create a fake ransom demand for both Hayley and Aurora's return, taking the reward money (funded through a hotline from Trish Turley's talk show) as ransom, and disappearing to Bermuda. Their plan is foiled by Veronica's discovery of Hayley's body and a phone call from the real Lee Jackson, who is a woman working for the Meridian Group specializing in ransoms and kidnapping. When Veronica concludes that Hayley was killed by her boyfriend, it becomes clear that it was an isolated incident. She quickly unravels the scheme, which ended up concluding in Aurora trying to double-cross her father and his partner.
Tanner is arrested, alongside his daughter and her boyfriend/accomplice Adrian Marks. Lianne faces the possibility of being tried as an accessory to the crimes, despite her lack of knowledge of her family's true intent.
In Mr. Kiss and Tell, it is revealed that Tanner was sentenced to two years in Ironwood State Prison for extortion and obstruction of justice.