Feathers Left Around

This novel is a murder mystery that revolves around the murder of Mr. Hugh Curran. Valentine Loft invited his fiancée, Pauline, friends, and Mr. Hugh Curran to his home for a party. During the party, they all discussed different methods of murder with Mr. Curran, a murder mystery novelist. Curran is discovered dead in a locked room the next day at Valentine Loft's home. Detective Kinney is on the case, but due to the interference of the other guests, he must enlist the assistance of Detective Fleming Stone. Who amongst the host and guest has the motif to murder Curran?