Helen Mirren won a 1996 Emmy playing Detective Chief Inspector Jane Tennison in the “Prime Suspect” mystery on PBS’ “Masterpiece Theatre.” Now she makes a strong bid for another Emmy as a burned-out 1960s rock star involved in another mystery, in “Painted Lady” on tonight’s “Masterpiece Theatre.” This two-part program, which concludes May 3, was virtually set up as a showcase for Mirren’s versatility, written exclusively for her by Allan Cubitt (“Prime Suspect 2,” “The Countess Alice”) with Mirren herself serving as associate producer. When we first meet her, Mirren is self-destructive Maggie Sheridan, a faded blues-rock star. Plucked from the verge of suicide by friends and treated for addiction to booze and drugs, Maggie has finally recovered and is living in obscurity on the estate of elderly Sir Charles Stafford (Iain Cuthbertson), her surrogate father, in a rural section of Ireland. But her tranquil state of mind is jeopardized one night when burglars break into the Stafford estate, steal a priceless painting, and commit a murder in the process. The more Maggie looks into the affair, the more scandalous it becomes. Could Sir Charles have arranged the burglary himself to get insurance money to help pay off the debts of his profligate son, Sebastian (Iain Glen)? Sebastian had the bad taste to run up debts with a malicious hood, who has made it quite clear Sebastian is dead meat if he doesn’t pay up. This all matters to Maggie because Sebastian is the one who dragged her out of her drug haze years earlier and probably saved her life. He brought her home to Sir Charles’ estate, where the elderly Stafford became, for her, the only father she’s ever known. She owes the Staffords a lot and is willing to put her neck on the line to help them.

Still, Maggie begins to learn about the family. For one thing, where did Sir Charles acquire his collection of paintings, most of thorn considered “lost art treasures since World War II? Maggies half-sister Susie (Lesley Manville), an art expert, and Susie’s husband, Oliver (Michael Moloney), agree to help her with the amateur detective work. Ultimately, the only way Maggie can gain the answers she needs and help Sebastian is to go undercover into the shadowy world of international art thieves, posing as a Polish countess with millions to spend on art. Her impersonation eventually leads her into the seductive world of the fubulously rich and doca-dently handsome Robert Tassi (Franco Nero), a mysterious art collector who soems intent on adding the countess to his collection, along wilh the art she owns. This is a spellbinding acting exercise for Mirren, who gets to be bluesy for half the film, then call upon her own ethnic heritago (she’s part Russian) to play the make-believe Eastern European countess. In the scenes where Maggie goes on a shopping spree to get herself decked out like a countess, you can almost see Mirren kick up her heels for the sheer pleasure of getting out of the dour, shopworn, tired look she usually wears in the “Prime Suspect” mysteries. Her well-known real-life sense of humor glows through this character. As for the singing on the soundtrack, it sounds a bit like Mirren but isn’t. Mirren admits she tried to sing the part but didn’t pass muster and had to be dubbed.

Like many British mysteries, “Painted Lady” is intricately woven and requires rapt attention to understand where things are going. But Mirren’s industrious performance is so much fun that you really don’t even need to know whore things are going to enjoy the ride. For Helen Mirren fans, and they’re becoming legion, “Painted Lady” is “must see TV.”