In the story's first part, Holmes tells Watson to read an anonymous letter that he recently received. Watson embeds the letter into his narrative, thereby giving the reader a chance to read it as well. The letter is marked by a distinct dialect, which confirms Holmes's suspicion that its writer is German:
There will call upon you to-night, at a quarter to eight o’clock [it said], a gentleman who desires to consult you upon a matter of the very deepest moment. Your recent services to one of the royal houses of Europe have shown that you are one who may safely be trusted with matters which are of an importance which can hardly be exaggerated. This account of you we have from all quarters received.
Throughout the story, the King of Bohemia speaks English in a unique way. As in this letter, Doyle plays with diction and grammar to emphasize both that the king is foreign and that he is a member of the nobility. Although all of the sentences in the letter contain unusual elements, Holmes and Watson devote their attention to the third and final sentence.
To begin with, the stationery that the letter is written on contains clues that lead Holmes to believe that it comes from Bohemia. Further, the language that marks the letter lead Holmes to confirm that it has been written by a German-speaker. In reference to the letter's final sentence, he tells Watson that "A Frenchman or Russian could not have written that. It is the German who is so uncourteous to his verbs."
Throughout the story, characters' disguises have varying degrees of success. This letter forms an essential part of the king's attempted disguise, as it claims that Holmes's visitor will be there on behalf of the king. However, the letter is also a part of his uncloaking, as it allows Holmes to deduce the writer's true identity. This ultimately shows that the king is rather naive and certainly that he is no match for the astute Sherlock Holmes.
