'The Good Liar' review: Entertaining but contrived thriller

Ian McKellen and Helen Mirren play elderly singles who swipe right in "The Good Liar," a classy but only half-convincing mystery-thriller about an internet date that is anything but casual. With those two stars, it barely needs saying that the movie's faults lie not in the acting. Like so many twisty-turny tales, "The Good Liar" hooks us quickly and keeps us guessing, only to disappoint in its final minutes.

McKellen plays Roy Courtnay — or at least that's the name this life-long con artist is using in London circa 2009. One minute, he's a well-dressed financier with a portfolio of tropical real estate. The next, he's a working-class widower gamely looking for love on the web. The latter persona is the one he presents to Betty McLeish, a well-educated and financially secure retiree played by Mirren. On their first date, they both admit they used aliases online. The ice is broken, trust is established and a courtship begins.

Roy's favorite con is age-old and time-honored: He puts money in a pot. Yours follows. And when the pot disappears, so does Roy. (Jim Carter, of "Downton Abbey," plays Roy's dignified sidekick, Vincent.) When the ruse works, it's simple and airtight. When it backfires, Roy isn't above using hired muscle to break a few bones. In one unexpectedly savage scene, the frail-looking gent even gets his own hands bloody. Clearly, Betty is in real danger, and we start to welcome the presence of her protective, college-age grandson, Steven (Russell Tovey).

We gather it's no coincidence Steven is studying Nazi history, just as we can tell Betty is smarter than she lets on. (Has Mirren, an actress of glittering intelligence, ever played a dope?) What we don't know is where all these threads will lead us. Director Bill Condon, of the final "Twilight" films, and writer Jeffrey Hatcher, working from Nicholas Searle's novel, pull us along from one reveal to the next, while Mirren and McKellen (now on his fourth collaboration with Condon) dance around each other elegantly.

It's mostly good fun, though the final plot contrivance feels like a letdown. Still, with McKellen and Mirren for company, you could do a lot worse than "The Good Liar."