In what I think of as the classic Silver format, we would have a chapter or two of character development wherein the problem that will eventually spawn a murder is followed by one of the star-crossed lovers appearing at Montague Mansions to engage Maud Silver, governess-turned-PI (if she isn't already in the neighbourhood on other business). This book stretches that format; Maudie doesn't appear until chapter 17 of 45, after the murder has taken place, which might contribute to the book's unpopularity, although it's not the deciding factor. The fact that one of the female leads is a spineless clinging vine probably holds that honor, when coupled with the notion that she's supposed to be a sympathetic character - unlike, say, Sylvia in MR. ZERO, who was an exasperating responsibility to the heroine without playing one of the romantic roles. She *is* more sympathetic than her counterpart in MR. ZERO, but aggravating at the same time.
Bill Waring, collecting his wits in hospital after a train crash, received only one letter from Lila Dryden, his fiancee. The next thing he knows, Lady Dryden, Lila's guardian, has pressured her into an engagement with Herbert Whitall, and she's on the brink of marrying him. As with Sylvia in MR. ZERO, this spineless person has a good friend, her bridesmaid and first cousin Ray - but unlike Sylvia, Lila's been steamrollered into this position rather than deliberately seeking a well-feathered nest, and both Lila and Ray have other romantic interests - Ray really cares about Bill Waring, and it's she who eventually calls in Miss Silver.
Herbert Whitall quickly emerges as the victim-in-waiting. He's aggressive, with a cold-hearted possessiveness that expands past the bounds of his ivory collection: he can't bear to lose. Millicent, his secretary and sometime mistress, planned to leave when he married, but he's kept a hold on her via a forged check. Lila is terrified of him, and the one person devoted to Lila - Whitall's architect, Adrian Grey - wants to protect her. Lady Dryden appears to have more than one motive for wanting her ward to marry well. Whitall even seems to have a hold on the butler. When a dagger in his collection becomes a murder weapon, one is spoilt for choice in terms of motive. Maud Silver - Edwardian gentlewoman with a soul of steel - must see that justice is done, not to avenge the guilty, but to protect the innocent.