Elementary season 4, episode 22 calls Holmes and Watson to the scene of a triple homicide. Could this staged robbery gone wrong turn out to be an assassination? Find out in an exclusive sneak peek!

Secrets are no fun, especially when someone winds up assassinated. For a few weeks now, a lot of things have gone unsaid in the Holmes-Watson brownstone. Joan skirts off to take care of friends and family while Sherlock is left to ponder why his partner is suddenly keeping him in the dark. Not wanting to press the issue, Sherlock has let most of her absences go unmentioned, but last week he began to scratch the annoying itch left by Joan’s blatant deceit.

The close of “Ain’t Nothing Like the Real Thing” revealed that one of the victims in the shooting was Emil Kurtz. Joan established Kurtz as an asset after discovering that he was the mole inside Morland’s office leaking contracts and information to competitors. The episode saw the two meeting clandestinely in a book shop where Kurtz still acted as a double agent, but this time he was keeping his day job while offering Joan information about Morland on the side. But Kurtz grew worried that Morland was after him when a few memos were marked with a trace to follow any leaked information back to the traitor. Kurtz called off his arrangement with Joan and cowered back to Morland’s employ. But not for long.

Joan gets one final good look at Emil Kurtz in “Turn It Upside Down,” and the expression on her face is enough to give away her weeks worth of lies to Sherlock.

This episode marks another milestone for Watson’s alter ego, Lucy Liu. “Turn It Upside Down,” is Liu’s third directing credit on the show. Her dedication to the role of Watson is just one way that Liu finds she can immerse herself in the larger scope of the series. Directing is another. “There’s something to be said about caring about what you do, loving what you do and that love hasn’t faded or waned, it has grown over the years,” Liu says in an interview about her return to the director’s seat this season.

Previously, Liu took on season 2, episode 22, “Paint it Black” in which she was kidnapped and forced to operate in her holding place until Mycroft revealed his true identity and called in a favor from MI6. In season 3, Liu helmed episode 14, “The Female of the Species” that followed Sherlock and Detective Bell through a case involving a pair of stolen zebras.

Another interesting facet of “Turn It Upside Down” is the face-to-face meeting Morland Holmes will have with Captain Gregson. What does Sherlock have in mind for these two to discuss? We’ll have to wait and see!

Elementary season 4, episode 21, “Turn It Upside Down,” airs Sunday, April 24 at 10:00 p.m. ET on CBS.