Take one grand house, stuff it with staff, and make it home to several generations. If they send their sons to Oxford and occasionally knock each other off, you’ve got a country-house mystery, that classic of English crime fiction. But if the boys are at Yale, odds are that you’re reading a New York mansion mystery — a genre largely invented by Elizabeth Daly.

Henry Gamadge, Daly’s gentleman-sleuth, does make occasional jaunts to the country, but now he’s back on the Upper East Side, receiving missives suggesting that all is not right at the elegant Fenway manse. But first he must find out who the messages are from.

The arrival of the first anonymous note convinced Henry Gamadge it was essential he get himself invited there to tea. But once inside, he found only a cozy family group. A young fellow called Craddock watched over poor half-witted Alden. Lovely Belle sat serenely in her invalid chair, attended by the competent Miss Grove. The somewhat sardonic Miss Caroline made charming small talk with her wealthy father and elderly cousin Mott. Even Gamadge couldn't guess which of them had just slipped him a second secret message-or how important a clue it would become in a most diabolical case of murder.