I pretended to be more tired than I was.

I let them see me repeat a question now and then, let them believe the confusion they wanted to believe.

And I set out, very carefully, a series of tests.

I left an outdated account statement inside an unlocked drawer, a statement whose balance was wrong, deliberately, by exactly eighty thousand dollars.

Three days later, Michael mentioned that exact incorrect figure while speaking privately to Rachel, which told me he had been through my drawer.

So I built another test.