I've been randomly looking for this fic for a while now, and it's driving me bug-hunting. It's genfic, with the team trapped in a cave (I think; it may be a cell, but I'm really leaning toward cave). Steve in particular is -- call it disbelieving when Tony announces he can get them out if they'll give him about an hour. He did awesome advanced math and physics in his head, which had Clint gaping, and when it worked, Bruce and Natasha were the only ones not surprised. I know that's not a lot to go on and I apologize for that. Here's hoping it rings a bell.
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