He didn’t solve it in a flash. It took him an hour. He filled the board beside Dr. Emory’s challenge with tight, elegant symbols: modular forms, L-functions, a twist on Langlands that he’d dreamed up while buffing the floors of Room 217. At 3:15 AM, he stepped back, erased a small mistake near the bottom, corrected it, and then finished mopping.
Marcus didn’t come back the next week. Or the week after.
“Who cleaned this wing last night?” he demanded.
Marcus didn’t look up. “I wrote a proof. Not the proof. I made an error in the fourth assumption.”
He left the mop in the bucket. He walked out of the math building, across the campus he’d cleaned for nearly a decade, and sat on a bench in the rain. He took out his phone. He looked up Dr. Lena Okonkwo’s number.