In fact, so ridiculously entertaining is this fourth chapter of an uneven franchise, it may very well make my list of the year’s best films. This is pure Hollywood product at its unapologetic, blockbusting best.

Tom Cruise returns as IMF agent Ethan Hunt, now sprung from a Russian prison to infiltrate the Kremlin and prevent nuclear war. That’s all a MacGuffin, of course, to get Hunt and his three teammates moving from one set piece to the next, each impressively larger in scope and stakes than the one before.

The exciting opening is fluff compared to the climactic showdown between Hunt and a missile-happy madman (Michael Nyqvist, “The Girl with the Dragon Tattoo”) amid levels of varying heights in an automated parking structure.

Most exciting of all is Hunt scaling a Dubai hotel with gecko-grip gloves, proving director Brad Bird’s (“The Incredibles”) move from animation to live-action as seamless. He improves upon J.J. Abrams’ underappreciated 2006 “Mission: Impossible III” while making “Protocol” a direct continuation.

From “III,” Simon Pegg (“Star Trek”) reprises his comic-relief role, now upgraded to field agent. New to the team are Paula Patton (“Precious”) as a stunner of an ass-kicker and Jeremy Renner (“The Town”) as an intelligence analyst whose fists are as fast as his thoughts.

Both fit so snug, one hopes they’ll survive the “M:I” revolving door to return for chapter five.