Murder Takes a Partner — Haughton Murphy

A death at the ballet draws Reuben Frost into a backstage conspiracy
 
While striding down Fifth Avenue, reveling in the beauty of the city, Reuben Frost loses his footing -- and is caught by a ballerina. Hailey Coles is a slip of a girl, but her firm grip keeps the retired lawyer from crashing down to earth. Soon, Frost will have a chance to return the favor. When the stage of the National Ballet is darkened by murder, only he can ensure that the show will go on.
 
Clifton Holt is a brilliant choreographer, but as an artistic director, he's made enemies of everyone from the boardroom down to the corps de ballet. When he's found stabbed to death at the stage door, it's assumed to be the work of a single desperate mugger. But Frost smells a more complicated plot, and he vows to find the killers before the final curtain falls.
 
Murder Takes a Partner is the 2nd book in the Reuben Frost Mysteries, but you may enjoy reading the series in any order.