Ezra Barnes as Sherlock Holmes, Brian Lee Huynh as Dr. Watson and Isabelle Van Vleet as Irene Adler in “Sherlock Holmes: The Final Adventure” at Portland Stage. Photos by No Umbrella Media, LLC

“My entire life has been a frantic attempt to escape the dreary commonplace of existence.” So says legendary detective Sherlock Holmes in the latest offering from Portland Stage. And the fictional but nonetheless immortal Holmes has graciously allowed fans of a good mystery to escape with him.

Steven Dietz’s 2006 play “Sherlock Holmes: The Final Adventure,” based on an original 1899 play by William Gillette and Sir Arthur Conan Doyle, combines two Conan Doyle stories to provide one good, old-fashioned time at the theater. Under the direction of Kevin R. Free, Portland Stage has put together a highly entertaining couple of hours of comedic melodrama set in 1891.

The scene is set when Holmes and his friend and assistant Dr. Watson, who occasionally narrates the play’s off-stage action, begin their trademark banter at the detective’s London apartment. Holmes teases out facts from the slimmest of clues. He admonishes the befuddled doctor at one point: “Oh, you see, Watson – but you do not observe.” Simultaneously annoyed and impressed by the master’s insightful deductions, Watson can only shake his head.

Enter the King of Bohemia, a comically overwrought monarch who hires Holmes to retrieve an embarrassing photograph from his former lover Irene Adler, a retired singer upon whom, though he is loath to admit it, Holmes coincidently has a crush.

Things get further complicated when Holmes’ arch enemy, Professor Moriarty, and his band of criminal conspirators, including James Larrabee (Michael Grew), Madge Larrabee (Laura Darrell) and Sid Prince (Zion Jang), get in on the action via an extortion plot.

Barnes as the title character in “Sherlock Holmes” at Portland Stage.

Ezra Barnes is a rather imperturbable and soft-spoken Holmes, concealing his true passion under a guise of clever plotting to get the photo back and Moriarty behind bars. Watson, who is for Holmes “a fixed point in a changing age,” nonetheless flits about quite a bit in Brian Lee Huynh’s portrayal. He struggles to keep up, as indeed might the audience also without his character’s help, as the action moves to the European continent. Affectionate dialogue and star and sidekick physical dynamics realize the relationship.

The mostly comedic roles of the others are ably filled. Isabelle Van Vleet provides an intellectually nimble Irene to counter the occasionally sexist views of Holmes. Nicholas Mongiardo-Cooper is a hilariously excitable King. Tom Ford’s Moriarty is an appropriately snarling adversary while his character’s gang members provide chills and laughs as their incompetence is revealed. Zion Jang’s Sid Prince is a particular hoot in the second act, when the comedy broadens considerably, along with the action.

Set design by Anita Stewart makes use of period furniture, a revolving center stage and a catwalk high above to frame the story. The costumes by Shireen Unvala, particularly those worn by Van Vleet, catch the eye. Lighting by Weston Wilkerson gently focuses the attention, and bits of piano music add tone to a show that brings classic characters back for a welcome return visit to a local stage.

Steve Feeney is a freelance writer who lives in Portland.