Sherlock (Jonny Lee Miller) and Joan (Lucy Liu) will take on a case involving a copycat killer in the upcoming episode of the CBS series "Elementary."

In "A Burden of Blood," CarterMatt reports that the pair will be tapped to investigate a homicide. Sherlock and Joan will be startled to learn that the modus operandi of the killer is the same with that of a notorious criminal. What makes the case baffling is that the infamous serial killer is already in jail, so who is the monster who recently took an innocent life? It appears that they are looking for a copycat, someone who has taken it his mission to continue that demonic work of his hero.

Meanwhile, Detective Bell (Jon Michael Hill) will find himself being tutored by no less than the two best specialists in New York Police Department. Sherlock and Joan will be helping him ace the police sergeant's exam. While this may be a nice thing to do, coaching a newbie, Sherlock may have a different motive altogether. He could be assisting Bell just so he would get the promotion and be sent to a new post. This maybe because Sherlock is jealous of the relationship between him and Joan. The promo shows he is getting suspicious on why his partner likes to spend time with Bell.

Last episode, Sherlock probed the grisly death of a retired FBI agent. His body was discovered shredded by a wood chipper and evidences point out that he knew his attacker. His ex-wife told the investigator that the victim was working on an old case. Sherlock had to dig deep to find that the agent was very interested with the kidnapping of a 10-year-old girl who was returned to her parents after missing for a decade. It turned out that the girl was a fraud and she was the primary suspect for killing the agent. Sherlock was not able to prove that she did the crime, though, as the episode ended with out a resolution.

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