The mountains outside Vancouver are picture-postcard gorgeous. One of them used to do double duty as the headquarters of a covert organization tasked with preventing nuclear winter. Now the installation resembles nothing so much as a radioactive salad bowl, nine-tenths of the group's personnel are dead, and the ones who are still alive are snapping at each other in the penthouse suite of a D.C. Marriott.
But cheer up! Things are only getting worse. An ex-agent is on national TV, their field-clueless neurosurgeon has blown the remains of their security, and the most senior agent who's still alive is determined to play James Bond... even if it means her aneurysm pops. Meanwhile, the same people who dropped a nuke on their base are wreaking havoc on the general population. They're starting with Three Mile Island re-enactments and heading for Chernobyl and beyond. Can they be stopped? Undoubtedly. Can they be stopped in time? Ah, there's the rub....
oh good, nuclear winter as a plot device. I'll get my sweater.
Clearly this is supposed to be a comedy, and the writing supports that so I'd be willing to grant you the premise of anyone surviving a direct nuclear strike.
You'll need to be specific about the hero, and the antagonist (none of this shadowy force of doom crap either). You've already laid out the stakes: the by now to be expected "saving of the world".
Since I'm in favor of fiery conflagrations, before breakfast if at all possible, this would appeal to me but you'd have to sharpen the hook before I'd ask for pages.