Jonny Lee Miller as Sherlock Holmes, Lucy Liu as Dr. Joan Watson, and Jon Michael Hill as Det. Marcus Bell
A mysterious woman who organizes illegal, high-stakes poker games arrives on Holmes and Watson's doorstep and tells them her life is in danger—and also claims to be a former associate of Mycroft, Sherlock's brother. However, as the pair investigates, Joan becomes suspicious that their new client isn't being truthful.
"All In" (Season 4, Episode 19 of Elementary)