On 2 September, German Chancellor Angela Merkel revealed that Alexei Navalny, a Russian opposition politician, had been poisoned with a nerve agent “identified unequivocally in tests” as a Novichok—one of a family of exotic Soviet-era chemical weapons. Merkel, a chemist by training, did not reveal the nature of the tests, conducted in a military lab in Munich. But scientists familiar with Novichoks have a good idea how the toxicological sleuths went about it—and are impressed at how fast the culprit was unmasked.