When investigator Ebenezer Gryce and lawyer Everett Raymond look into the case, it is revealed that no one could have left the Manhattan Mansion before the body was discovered the next day.

As the story progresses, Leavenworth's orphaned nieces Mary and Eleanore, Hannah the maid, and a mysterious gentleman who appears on the scene all factor into the investigation.

[7][6][5] Green's New York Times obituary calls The Leavenworth Case her most famous novel, and claimed after the author's death in 1935 that many copies were sold and that it was still popular.

[6] Three different publishers (Alexander Strahan, Ward, Lock & Co. and George Routledge & Sons) pirated the book in 1884, and this continued to be a problem throughout Green's career.

[8][3] Green used her familiarity with criminal and legal matters to create a novel that is characterized by technical accuracy and realistic procedural details.

[11] Green's investigator, Ebenezer Gryce, was introduced nine years prior to the publication of Sir Arthur Conan Doyle's Sherlock Holmes stories.

[12] By locating the action of her stories in America, Green distinguished herself from earlier authors of detective fiction who had set their works in Europe.