CLASSY, solid and well-acted, The Debt is a rare bit of meaty, intelligent filmmaking during the ordinarily dreary final days of summer.

With a cast that includes Helen Mirren, Tom Wilkinson and a tremendous Jessica Chastain, led by Shakespeare in Love director John Madden, it seems it would be hard to go wrong. Matthew Vaughn, the director of Layer Cake and Kick-Ass, co-wrote the script. It’s smart and tense but also frustrating; it almost feels too safe, too conservative and reserved in the way it hits its notes. Still, everything about it is so respectable, you may feel engrossed in the moment, yet forget about it soon afterward.

A remake of a 2007 Israeli film of the same name, The Debt begins in 1997 with three former Mossad agents being heralded at the launch of a new book that details their most important mission from 30 years earlier. They are Rachel (Mirren), her ex-husband, Stephan (Wilkinson), and their former colleague and friend, David (Ciaran Hinds). The former husband and wife are parents of the author, and the glances they exchange signal that they’re not too comfortable with being celebrated as heroes all these years later. The startling fate that befalls David also provides an early moment of foreboding.

Flashback to 1965. The exceedingly capable Rachel (Chastain) and the strong, stoic David (Sam Worthington) are pretending to be a young married couple trying to have a baby in order to get close to an East Berlin doctor named Dieter Vogel (a chilling Jesper Christensen), a Nazi war criminal known notoriously during World War II as the Surgeon of Birkenau. Under the leadership of the swaggering Stephan (Martin Csokas), the team is to kidnap Vogel and bring him back to Israel to stand trial.

Despite their training and focus, this does not exactly go as planned, and the ways in which the agents fail are more interesting than the build-up of watching them function in high

gear. Madden proves himself surprisingly adept at crafting this kind of brainy, brawny action thriller with a mixture of well-placed silences and visceral camerawork.

As it jumps back and forth in time, The Debt explores the conflict between expectations and reality, intellect and emotions, truth and regret. The film’s grey areas are so intriguing that you’ll wish it didn’t rely on a facile love triangle to create further tension — and add yet another layer of history — between these three characters. The needless romance further bogs down the third act, which grows unfortunately messy as it tries to tie up various loose ends and satisfy the audience’s need for justice.

Still, the performances are consistently strong, especially from Chastain in a far more grounded, muscular role than we’ve seen from her this year in The Tree of Life and The Help. Meanwhile, Mirren can do tough-but-vulnerable in her sleep; these two are the most plausible duo of the three. As exciting and confident as Csokas is, it’s hard to believe he’ll morph into Wilkinson eventually, and Worthington-to-Hinds is the most baffling of all.

Unless maybe we’re supposed to believe that all those years of secrets and lies have really taken a toll.