All build-up, then -- fizzle.
There's this crazy cast of (to me rather annoying and unlikable) characters: the family of rich eccentrics, lounge musicians, drug dealers, magazine columnists... and then once we get the relationships and plot all worked out, it's over. Disappointing. I felt bad for the one pleasant character, having to put up with selfish jerks, and gropey creeps and murder and then not even getting a denouement.
And I know Marsh stereotypes of Italians and "Latins" is par for the time, but it gets a tad irksome of you read more than one mystery with an Italian/Spanish/Latin American character in a row.