Gregson's boss wants to chat with him about the future of the unit.
Bees are dying out. Everett Keck, from the USDA, is investigating bees dying at a local bee farm. The owner finds a bunch of dead bees and a dead Everett.
There was an egg carton dosed with cyanide placed in the smoker which killed Everett. Sherlock suspects AgriNext. Joan gets a call from Gregson that he needs to see her.
Gregson was offered the Deputy Chief position. He wants Joan to check out his replacement.
Sherlock meets with AgriNext. They had a strong counter response to Keck's claims and deny any involvement in his death.
Sherlock asks Joan if the Captain is leaving.
He believes he found Keck's killer. A disgruntled bee keeper, Jarvis, confesses to killing Keck but claims that Keck killed his bees.
Sherlock believes him. Keck's supervisor had an heart attack, which put the investigation on Jarvis' claims on hold. Sherlock believes Keck poisoned his boss and Keck was responsible for the bees deaths. Sherlock speculates Keck had a partner.
Joan and Sherlock meet with Cal's wife. She thought there had been a struggle. Sherlock agrees with her.
Joan speculates because funding has dried up that maybe an academic researcher is behind the deaths. They get a guest list of those attending the summit on the Colony Collapse Disorder, which includes a reclusive Sheik.
Joan meets with a handwriting expert who gives her bad news.
Sherlock goes to the Sheik's hotel and discovers he has been kidnapped.
Rashid, one of the sheik's security guards, is missing and assumed to be part of the plot.
Joan tells Gregson that Lt. Vancey is clean. He doesn't know what to do.
Sherlock and Marcus visit some pawn shops who have some of the sheik's belongings. One of the laptops Rashid bought has GPS installed. Police arrest him. He claims the Sheik was with a prostitute and then they both disappeared. He ran out of fear. Sherlock believes him.
They interrogate Tara and Griffin Parker separately. They deny involvement. Tara suggests they call the Sheik. He has been returned and is on his way home.
Gregson has to cut them loose since the Sheik denies being kidnapped. Sherlock looks for evidence against the attack against Calvin Barnes.
Tara was having an affair with Everett. Once Griffin found out, he turned against her.
Gregson declines the promotion. He learns that he was supposed to take the job, but doesn't know why.