Sherlock Holmes is dead. If he ever lived in the first place, that is.

So is Jeremy Brett, who really did live and who played Holmes for PBS-TV’s “Mystery” series for many years.

So, for that matter, is Arthur Conan Doyle, who created the Holmes series, inspired by the forensic legerdemain of his mentor at the University of Edinburgh Medical School, Dr. Joseph Bell.

Bell is dead, too.

But “Mystery,” which knows a good thing when it sees an audience respond, has managed to eke out another Holmesian chapter. Airing this week and next on PBS is the two-part “Murder Rooms: The Dark Origins of Sherlock Holmes.”

It has long been known that Doyle modeled Holmes after Bell. But this new drama is based on recently discovered private letters and papers belonging to Bell that show he was secretly involved in criminal investigations for the Crown. And “Murder Rooms” is a guaranteed audience pleaser, full of all the factors that made fans of the Holmes TV series so happy: a Victorian setting, a master sleuth whose specialty is deductive reasoning, an earnest sidekick who lags just a step or two behind the master in seeing the meaning behind the seemingly innocuous clues, and characters with a certain … well … savoir faire.

This new “Mystery” begins to unfold as young Doyle (Robin Laing) meets Bell (Ian Richardson), a professor at the Edinburgh medical school who maintains that the same reasoning that is applied to the discovery of what ails a patient can be used to uncover evidence of a crime. Doyle at first sees Bell’s astonishing deductions about his patients as mere parlor tricks. When he inadvertently lets Bell know of his disdain for the technique, Bell, instead of rebuking the young student, adopts him as his assistant. In short time, Doyle learns that Bell is a much more complex personality than he had first thought.

Set in 1878 as the university is bedeviled by new policies mandating the admission of women to the medical school, the plot finds Bell and Doyle — in their best Holmes/Watson mode — involved in a case of murder and suicide as they race against time to prevent still another death. Further complicating matters is a new classmate for Doyle, a beautiful young woman named Elspeth (Dolly Wells), who may or may not be next on the list of victims. And just as in Holmes’ cases, the police don’t always welcome the assistance of laymen.

Richardson adopts the occasional Holmesian gesture and attitude in creating Dr. Bell as a wonderfully eccentric and brilliant teacher, and Laing, who has no template from which to work, nevertheless succeeds in making Doyle an engaging, fascinated and fascinating student. As always, this joint BBC-TV and WGBH-TV production succeeds masterfully in recreating the dark and compelling aura of the Victorian era.

After such an initial success for “Murder Rooms,” viewers will surely be clamoring for more about the young Doyle and his medical-school