Dancers in Mourning (1937), Margery Allingham's 9th Albert Campion novel, is not, as described in the blurb in the Crime & Mr. Campion omnibus, a "novel about the world of the ballet."
The titular dancers, rather, are of the musical revue sort, and the first third of the novel functions as something of a satire of the genre, as well as providing the template for Simon Brett's Charles Paris series.
Dancers in Mourning loses narrative steam in the second half as a suicide becomes more and more obviously a murder and the novel moves from backstage intrigue to a police procedural set in a country manor.
As a premonition of the coming war, Allingham shakes up the proceedings with a truly unexpected murder by grenade. And if three deaths weren't enough, Allingham adds a brutal bludgeoning by spanner.
Lugg appears only briefly but manages to say this about Campion:
"Got yourself mixed up in a suicide now, I see. People lay themselves open to somethink when they ask you down for a week-end, don't they? 'E's a 'arbinger of catastrophe."
In addition to trying to solve the murders, Campion also must come face to face with a moral dilemma. As a police inspector comments, "Right's right and wrong's wrong. He knows that."
Three-and-a-half daggers out of four.