A young woman, Allison Cowley (Mena Suvari), comes into the Santa Barbara, California police station claiming to have just escaped after being kidnapped and held by the notorious serial killer Mr. Yin.
Shawn Spencer and the police are wary to believe Allison, as several others come into the station making similar claims involving the Yin case.
While being questioned by Shawn and Gus, Allison describes being shackled to a radiator by Yin and shows them a bruised wrist as proof.
With Allison missing and the clock ticking, Shawn turns to Yang for assistance on finding her partner, Yin.
They all arrive back at Henry's, who has been trying to figure out where the picture was taken and even called his ex-wife Madeleine (Cybill Shepherd) for help.
They ask the dean for information on the missing Professor Karl Rotmensen, but everything on his CV turns out to be false.
Rotmensen's home address is actually an empty field, where they find VHS tapes about Yin and Yang that Mary Lightly (Jimmi Simpson) had made for Shawn before his death.
Upon arrival, they hear a recording of Madeleine's voice calling from inside, leading them to proceed before waiting for backup.
Yin (Peter Weller) binds Shawn and Gus and begins filling a syringe with a lethal concoction.
Yang asks Yin if she can "come home" and resume helping him, to which he reluctantly agrees, pulling her into a fake fatherly embrace.
Shawn points out to Yang that she is innocent of the murders for which she was convicted, but she admits guilt for allowing Yin to continue.
Due to special guest star Cybill Shepherd's schedule, "Yang 3 in 2D" was forced to be filmed before many of the preceding episodes.
Guest stars Ally Sheedy and Jimmi Simpson also returned as their respective characters Yang and Mary.
The episode was viewed by 2.90 million people (on the original airdate),[2] which was down roughly 50 thousand viewers from the previous season finale ("Mr. Yin Presents...").