Summoned one evening to the house of a bedridden man — and taken there in a carriage with blacked-out windows to obfuscate the location — Dr. Christopher Jervis suspects poisoning but is assured by the people looking after Mr. Graves that no poison could have been administered. Some weeks later, he is summoned a second time and, after administering some treatment that sees Mr. Graves begin to revive, is dismissed and never hears of the patient or his carers again. Between these two visits, however, Jervis consulted Dr. John Thorndyke, which proves to be most fortuitous when further investigation into the matter becomes important.
