An interesting case will come to the attention of Sherlock (Jonny Lee Miller) and Joan (Lucy Liu) in the upcoming episode of the CBS series "Elementary."

In "A Study in Charlotte," Hollywood Hills reports that a mass murder will take place in a university. The investigation reveals that the killer used mushrooms to poison a botany professor and some of his students.

Sherlock and Joan will be looking at revenge as the motive to kill. Someone who has a grudge against the instructor decided to get even by outsmarting the victim in the field he was supposed to excel in. The use of the toxic fungus shows the killer knows what he was doing. The fact that he did not care that innocent people also died because of him indicates he has no conscience. How will Sherlock and Joan capture him?

Elsewhere, Trent (Richard Kind), Joan's new neighbor, is giving her a huge headache. The consultant will wake up one night after hearing loud sounds coming from Trent's house. When she gets out to investigate, she will learn that the man is using his own digs to earn some money.

Apparently, Trent is leasing his home as a venue for "hard" parties. It looks like Joan needs to get an extra pair of earplugs if she wants to sleep peacefully at night, especially when Trent refuses to forgo his new source of income.

Last episode, the narcotics division asked Sherlock to plan the perfect heist to infiltrate the compound of a biker gang involved in drug activities. He was partnered with the mole in the case, an undercover agent. It turned out there was no need for Sherlock's plans because when the officer turned up dead, the police was forced to raid the safe house and nail the culprit. It turned out the snitch stole all the money of the gang shortly before he died. His accomplice double-crossed him and ran off with the dough.

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