Sherlock Holmes (Jonny Lee Miller) is hired by the president (Reg Rogers) of a security company renown worldwide as the “world’s foremost maker of bank vaults” to discover how the company’s unbreakable safe was breached leading the the theft of $40 million in diamonds. Despite his initial assessment of needing only an hour to come up with the answer, the case proves to be far trickier than he originally believed. Maybe he should have stayed in bed with those twins (both played by Tonya Glanz) after all.
Unable to discern a way to break into the safe, Holmes turns his attention to who might have committed the robbery. Holmes talks with a member (Sean Dugan) of the only crew to ever successfully break into The Leviathan vault which leads Holmes and Watson (Lucy Liu) on the trail of a legendary thief known only as Le Chevalier. In a single afternoon Holmes is able to find Le Chevalier only to discover the infirm man was incapable of the recent robbery.
After digging through the trial transcripts of one of the original robbers leads Holmes to discover the algorithm which breached the vault as well as the identity of one of the jurors on the original robbery case who likely helped plan this new robbery. However, by the time Holmes gets around to questioning the juror the man has already turned up dead. Comparing the skill sets of the original robbers to those of the new robbery, Holmes makes a startling discovery that four of the jurors worked together on the new job, and now one of them (Gbenga Akinnagbe) is killing off his co-conspirators to keep the whole $40 million to himself.
Taking a momentary break from the case for dinner with Watson, her mother (Freda Foh Shen), and brother (Steve Park), Holmes takes the opportunity to champion the doctor’s new profession as a companion and commend Watson on her invaluable help on solving several recent cases. This, along with Watson’s mother visit in the final scene, continues the thread starting in last week’s episode to further bring Holmes and Watson together as more than just client and care provider, and open the door to Watson choosing to stay after her contract expires.