[2][3] Described as "being another of 'Kate Kirby's Cases', a series of detective stories", the plot summary in The Edison Kinetogram was:[4] Philip Morton, on the eve of his marriage to Alice Osborn, discovers that he is about to make a terrible mistake, since he loves her sister, Marguerite, more than his bride-to-be.

To the brilliantly apparelled guests awaiting the commencement of the ceremony in a drawing room, a maid suddenly appears with ghastly news.

Kate discovers the letter in Marguerite's portmanteau, and this, coupled with the significant fact that the knife with which the girl was killed is Morton's, leads to the immediate arrest of the suspected man.

In a vigorous third degree, the Chief attempts to get incriminating evidence for Marguerite, finally leaving her apparently alone with Morton in the hope that he will convict himself in her presence.

Near the edge of the banisters, she finds a slight mark, and immediately her keen mind solves the entire mystery.The Moving Picture World On The Broad Stairway (Edison).

One of the detectives is a woman, Laura Sawyer, and when the inspector, Robert Brewer, tries to wring the truth out of May, her sympathies are so worked up that she goes out to make further investigations, believing they will clear May and Bigelow.