It is 1868, the week that Benjamin Disraeli becomes Prime Minister of the Empire. Sherlock's beautiful but poor admirer, Beatrice, the hatter's daughter, appears at the door late at night. She is terrified, claiming that she and her friend have just been attacked by the Spring Heeled Jack on Westminster Bridge and the fiend has made off with her friend. At first Sherlock thinks Beatrice simply wants his attention, and he is reluctant to go back to detective work. He also believes that the Jack everyone fears is a fictional figure. But soon he is suspicious of various individuals, several of them close friends.


這是一八六八年，班傑明‧迪斯雷利甫上任帝國首相。外貌出眾、一心愛慕福爾摩斯的帽商之女貝蔕絲突然在深夜站在門口，神情驚恐，說她和朋友剛在西敏橋遭到彈簧腿傑克的攻擊，這惡魔還帶著她的朋友逃開了。起初，福爾摩斯以為貝蔕絲純粹只是要吸引他的注意，也不太想再重拾偵探工作，況且他認為這個人人聞之色變的傑克不過是個虛構人物罷了。不過，案件接連發生，其中還有幾樁就發生在周遭的朋友身上，他便馬上起了疑心。