Arthur Wordsmith is an unknown writer and an unexperienced eye doctor. In 1889, he receives a letter invitation to the Phantomhive mansion, at a party with several famous people. The earl seems to be fond of one of Mr Wordsmith's writings in a minor magazine and that remains the only reason why he invited him.
At night, one of the guests, Lord Siemens is being found dead in his room and this starts the Phantomhive Manor Murders. Due to the rain, nobody can leave the manor and they have to cope with the situation as others of them are being murdered (that including the butler, Sebastian).In this case, Arthur will play the role of the detective, desperately trying to find the culprit, even if at first it seems impossible. Later after Siemens death and before he was found murdered, Sebastian tell him that "he leaves the young master in his hands", this somehow making Arthur feel that something was not right in that manor. At the end of the arc, just after his carriage leaves the mansion, he wants to go back, thinking that he found an explanation to what has happened there. As he founds out that Sebastian is a demon, he is still not killed. The reason seems to be that now he was sure to write a masterpiece.