Maigret is secretly summoned by a distraught cabinet minister who needs help in recovering a document - the Calame report, an engineering study that warned that a government-funded children's sanitarium was of unstable design. The study was hushed up, the report stolen, and the disaster made reality - with 128 children killed in the building's collapse. Now Maigret must plumb the depths of government corruption to find the thief and the report - and let the compromised government fall where it may.