Chapter 11: Nadia's Water Case

The call came at 6:52 AM on a Wednesday, while Marcus was grading the third set of stoichiometry problems he had collected that week and finding, for the third time, that Okafor had set up her dimensional analysis correctly and then made the same arithmetic error in the final conversion — not carelessness, a consistent conceptual gap in how she handled unit cancellation, the kind of error that looked like a mistake but was actually a theory.

He picked up on the second ring.

"I need your brain," Nadia said, without preamble. This was her version of a greeting when she was working. He had learned to distinguish it from her version of a greeting when something was wrong, which was more silence in the first two seconds.