Elementary Enlists Mentalist Alum Owain Yeoman for 100th Episode

Owain Yeoman Elementary

Sherlock will get an assist from a familiar CBS face during Elementary‘s apocalyptic 100th outing.

The Mentalist‘s Owain Yeoman will guest-star in the milestone installment — slated to air Sunday, Oct. 30 — as Holmes’ boarding school classmate, TVLine has learned exclusively.

The hour, titled “Henny Penny The Sky Is Falling,” “revolves around the murder of a man who was looking for better and more efficient ways to identify what are known as Earth-killer asteroids,” executive producer Rob Doherty previews. “So there’s mystery on top of mystery as to why anyone would want to kill someone who might be able to help NASA locate and, hopefully, divert a small planetoid hurdling towards Earth.”

During the course of the investigation, Sherlock must turn to Yeoman’s character, a scientist, for assistance with the case. “It’s a fun and very colorful role,” Doherty adds.

Yeoman has for the past two seasons played Benedict Arnold on AMC’s TURN: Washington’s Spies. Other recent credits include guest stints on Extant and Supergirl.

Elementary Season 5 premieres Sunday, Oct. 2 at 10/9c on CBS.