Fitz-James O'Brien capitalized on the success of his predecessors Edgar Allan Poe and Mary Shelley in writing disturbing stories with demented protagonists, and this collection of three tales shows his mastery of the macabre. "The Diamond Lens" tells of a lone scientist's discovery of a microcosmic world within a drop of water, and his growing obsession with the beautiful Animula, a fair maiden within this world which he can see but never enter. His uncompromising pursuit of knowledge at any cost foreshadows the mad scientist familiar to readers in a multitude of works. In "What Was It?" an invisible man is discovered by residents of a boarding house. The residents' capture and investigation of the creature blends the fantastic with the scientific as they seek rational explanations for this extraordinary phenomenon. "The Wondersmith" is a macabre tale of an embittered toymaker who seeks revenge upon the society that has persecuted him by creating demonic mannequins and imbuing them with life in order to slaughter the masses—a fantastic melodrama in which the cunning Wondersmith is offset by the unassuming and unlikely hero Solon the hunchback, in love with the villain's daughter.