Sherlock (Jonny Lee Miller) and Joan (Lucy Liu) will track down the killer of an ultra rich Russian national and two other victims in the upcoming episode of the CBS series "Elementary."

In "Murder Ex Machina," CarterMatt reports that the pair will be tapped to investigate three murders purportedly instigated by a computer hacker. The case will be getting a lot of attention, as one of the victims is a Russian billionaire on a short trip in New York. Sherlock and Joan must find the culprit, but the cyber aspect of the case will prove to be difficult to crack down. Will they be able to flush out the killer and make him pay for all his crimes?

Meanwhile, Joan will be getting a surprise dinner invitation from Morland (John Noble). All the more intriguing is that it will be just the two of them together. What does Sherlock's father want with her? Is this another scheme to bring father and son together again? Even after showing that he is determined to win back Sherlock, Morland still has not breached the walls that the younger man has surrounded himself with.

Last episode, the daughter of a serial killer turned up dead. An unknown man suffocated her in her car. Evidences suggested that she knew her assailant. When the victim turned out to be eight weeks pregnant, Sherlock and Joan went to find her husband. It turned out he had a condition that prevented him from fathering children, so it was clear the woman was having an affair. This gave him motive to kill, especially once he learned of his wife's betrayal. His alibi, however, was airtight.

The concubine also had no idea she was pregnant. He also had a credible excuse for not killing her. It turned out the murderer was the woman's brother. They both made a pact in the past that they would never have children to end their father's blood line. His own two kids were adopted. When he learned that his sister was having a baby, he went ahead and killed her.

"Elementary" season 4 airs Thursdays at 10 p.m. EST on CBS.