Sherlock Holmes prevents Shinwell from going to jail when Shinwell is framed for a crime by Agent Calvin Whitlock. Whitlock was a corrupt detective who told Shinwell he was a CI but, Whitlock hadn't registered him as such. Watson asks Guzman to make Shinwell a CI but Holmes doesn't believe Shinwell has the skills to be one. Holmes asks Guzman to not make Shinwell a CI but, Watson is able to convince Guzman. ("Pick Your Poison") Guzman informs Holmes that someone tried to kill Shinwell during a drive-by shooting but his CI cover wasn't blown. Later, he tells Holmes that bullets recovered from the shooting match those from a 12 year old unsolved murder of an SBK lieutenant Shinwell knew named Jameel Clark. Guzman indicates he hasn't told Shinwell as he doesn't want him to take matters into his own hands. ("The Ballad of Lady Frances")
That sounds personal.
After Holmes questions Denton Clark, the brother of the SBK lieutenant killed 12 years previous, Guzman and Watson question him. His account points to Shinwell as the likely killer and Denton admits that he was behind the drive-by shooting. ("Dead Man's Tale") After Shinwell is killed, Guzman brings Holmes, Watson and Bell up to speed on SBK's hierarchy and identifies Bonzi Folsom as the leader for the last 13 years. He indicates it's a mystery how the gang communicates and that Bonzi receives no visitors. He also relates that Bonzi has a half-brother, Tyus Wilcox, who isn't part of the gang but hasn't been able to help the police. With Agent Burke's help, Holmes finds out that Bonzi and Wilcox's mother owes back taxes and could be used as leverage to gain Wilcox's co-operation. ("Scrambled")