Who says it doesn't pay to invest in new plays? Equivocation—a cinematic historical thriller by Father Bill Cain—could be the best advertising campaign the Oregon Shakespeare Festival has ever seen.

The play—a mystery involving William Shakespeare, Guy Fawkes, Catholic oppression under James I, and a wicked spymaster whose descendants are still powerful in Britain's Conservative Party—is pure OSF. It premiered at OSF 2009, stars six longtime OSF actors (with a collective 59 seasons between them), and was directed by OSF artistic director Bill Rauch. The set is a re-creation of the Old Globe Theatre, and even the costumes (and the small ruffs on the spymaster's socks) are direct from Ashland.

Fortunately for OSF, Equivocation is a fine-tuned pleasure machine: tense, fast, funny, extraordinarily clever (which allows audiences to feel extraordinarily clever), with rich and surprising characters, many jokes, many plot turns, and some gossip about the making of King Lear and Macbeth. What Shakespeare in Love did for the young, Elizabeth-era Shakespeare, Equivocation might do for the mature, James-era Shakespeare—maybe even on the big screen. One of the play's many achievements is its cinematographic staging. Lighting effects and layered writing and directing—21st-century actors playing 17th-century actors playing contemporaneous historical figures—allow for live-action crosscut and montage shots. The actors flip between characters, allowing scenes to crosscut (for example) from a dungeon to the Old Globe and back to a dungeon: a film trick brought to the stage.

The play's equivocations begin in the office of Robert Cecil, first Earl of Salisbury, statesman, spymaster, and secretary of state to the foppish and dim James I. Cecil has summoned Will "Shagspeare"—Father Cain, a Jesuit, says that's his favorite variation of the spelling—to commission a play. Shag is understandably wary: Cecil is Donald Rumsfeld plus Dick Cheney in black fur and a ruff. By way of making conversation, he upbraids Shag for writing Richard III as a villain. "He was a murderer," Shag protests. "They're all murderers!" Cecil shoots back. "He balanced the budget. People have no idea..."

Cecil wants Shag to write a "true history" of the recent Gunpowder Plot: a story of Catholic terrorists (including Guy Fawkes) who planned to tunnel under the House of Lords and blow up everyone inside. But James I, with a little help from God, foiled them. Cecil wants a play as "the official version of the event—so it will last." (The actors had to pause for the audience's long laugh.)

This is a dangerous commission: artistically, morally, and physically. Catholics were suffering landgrabs, torture, and execution under James I, and Shag's own father was a crypto-Catholic. But the money is good and the challenge is better: to uncover and tell the truth about the Gunpowder Plot—an adventure that occasionally sends the play in film-noir directions—without upsetting Cecil or King James. Telling multiple truths is Shag's specialty.

"With every new play, you raise the bar in the art of cynical manipulation," Cecil flatters Shag—telling kings they are to be pitied more than their subjects and telling poor subjects they have the dignity of kings, telling Jews they have a right to their rage and telling Christians they have a right to take the Jews' money and forcibly convert them. "And," Cecil concludes, "somehow everyone went away satisfied... an astonishing achievement."

(It is more than a little ironic that this play about the oppression of Catholics by intolerant brutes from the Church of England comes mere weeks after the Vatican announced it would welcome mass conversions of Anglicans who wish to flee the CoE's increasing friendliness to gays and lesbians. All those centuries of fighting, blood, and torture over theological differences wasted—all it took was a little shared homophobia to bring people together.)

The play runs nearly three hours, but Father Cain's writing is lucid and lean, and the actors have the tight, thrumming energy of a well-toned ensemble. Anthony Heald plays Shag with a world-weary but quietly hopeful energy, and Richard Elmore, as the cranky elder statesman of the King's Men, chews up the dialogue (and a younger actor or two). Christine Albright plays Judith, the twin sister to Shag's dead son Hamnet, with sardonic, fatalistic grace. "She'd depress a saint," Richard says, and he's right. But she's beautiful, smart, and gets all the soliloquies.

But the strongest magic comes from Jonathan Haugen as master manipulator Cecil. His voice is bewitching, shifting instantly from warm and unctuous to slashingly cold and sharp. Cecil, who brags about working straight through his wife's death, admires Shag's genius but must outmaneuver him: And he does, over and over again.

The play is full of Shakespeare in-jokes as the other characters, who depend on Shag's plays for a living, comment on them: His daughter scorns soliloquies ("As if you needed to know one more thing about Hamlet"), and his actors encourage each other through Lear's crazy storm scene ("If we got through his comedies-don't-have-to-be-funny period, we can get through whatever this is"). But our villain Cecil is the play's clearest-eyed critic, arguing like a 17th-century Harold Bloom that Shakespeare's work will become a civic religion, that it may outlive the Bible as a collection of stories, wisdom, and mystery, with none of the biblical prohibitions.

The Geffen Playhouse in Los Angeles has already snapped up Equivocation, which opened last weekend to mixed reviews. It was directed by David Esbjornson, of all people (he was hired as the Rep's artistic director in 2005 and left after three years), who put the actors in modern dress and, according to the LA Times, directed the comedy broadly in "sitcom italics." (Ouch.) The play will go to Manhattan Theater Club next year.

Seattle is lucky to have scored the original OSF production. I expect we are only the second stop on a long, successful road.