The Adventure of the Wax Gamblers by John Dickson Carr is a Sherlock Holmes story. The story was published in the 1954 collection, The Exploits of Sherlock Holmes, a joint enterprise of Adrian Conan Doyle and John Dickson Carr.
Plot
While waiting up late one night, Holmes and Watson are visited by the night watchman of a famous waxworks and his grand–daughter. The watchman has noticed that the playing cards in the hand of a wax figure in a Chamber of Horrors exhibit have changed. Holmes becomes immediately interested in this mystery and sends Watson to the exhibit to remove the cards in an orderly fashion and to bring them back to him in some envelopes. Holmes then demonstrates that the altered cards are related to the scandalous behavior of a gentleman and his wagering on horse races.
" ' At the mouth of the Thames,' " he read, " ' on the island of —' "
"Holmes, my question concerned the answer to our problem!"
"This is the answer to our problem."
Two versions of the Darlington Substitution Scandal, which had been mentioned in A Scandal in Bohemia, are referenced in this story.