Law & Order: SVU Season 20 Episode 12 involves a serial rapist who the late Ben Stone was obsessed with bringing to justice.

When a young woman is raped and her husband tied up, SVU quickly recognizes the MO of the Infinity Rapist, a serial rapist who last struck in 1994. They also discover that Ben Stone worked on the original case, and Stone finds a photo of himself as a child when he looks at the case files.

Carisi realizes this rapist is a copycat. They find a young guy who is obsessed with the Infinity Rapist and who insists he's the original even though he's far too young. After his arraignment, a reporter approaches Stone about covering this case, but Stone declines to help her. One TV interview with the perp later and she is raped -- by the original Infinity Rapist.

Carisi looks for other letters written by the Infinity Rapist and manages to get DNA off a stamp. He runs it through a genealogy site, which leads him to a young woman whose uncle fits the description. She doesn't believe it and the uncle denies it.

In court, Edgar's defense attorney gets the case dismissed on 4th Amendment grounds because Carisi used the genealogy site to find Edgar. Carisi and Stone keep digging and find that Edgar was obsessed with Ben Stone and considered him a father figure. They use this to get a confession.

Meanwhile, this case brings up painful memories for Stone, but he is able to use his past to help Noah.

To find out what happens, watch Law & Order: SVU Season 20 Episode 12 online.