The IMF is now disbanded and a syndicate is putting effort to ensure it is completely destroyed.
Ethan gathers his team and joins forces with Ilsa Faust; a disavowed British agent who may or may not be a member of this deadly rogue nation.
There's a kind of soldierly camaraderie among the agents, who constantly find themselves betrayed by politicians, military officers, and even their own commanders, and they band together to save the each other along with saving the world as we know it.
Writer-director Christopher McQuarrie, whose action movie skills are at best high-adequate, compensates by being good at interpersonal stuff. He can make us feel for the characters as something more than action toys.
You don't overcome the "impossible" by thinking it over a little more carefully. You overcome it through the application of sheer, unvarnished willpower, a quality that Cruise has always possessed in abundance.