Rouletabille, after examining it minutely, returned it to Larsan, with a bantering expression on his face, saying:—
“You were given a French cane in London!”
“Possibly,” said Fred, imperturbably.
“Read the mark there, in tiny letters: Cassette, 6a, Opera.”
“Cannot English people buy canes in Paris?”
When Rouletabille had seen me into the train, he said:—
“You ’ll remember the address?”
“Yes,—Cassette, 6a, Opera. Rely on me; you shall have word to-morrow morning.”
That evening, on reaching Paris, I saw Monsieur Cassette, dealer in walking-sticks and umbrellas, and wrote to my friend:—
“A man unmistakably answering to the description of Monsieur Robert Darzac—same height, slightly stooping, putty-coloured overcoat, bowler hat—purchased a cane similar to the one in which we are interested, on the evening of the crime, about eight o’clock. Monsieur Cassette had not sold another such cane during the last two years. Fred’s cane is new. It is quite clear that it ’s the same cane. Fred did not buy it, since he was in London. Like you, I think that he found it somewhere near Monsieur Robert Darzac. But if, as you suppose, the murderer was in The Yellow Room for five, or even six hours, and the crime was not committed until towards midnight, the purchase of this cane proves an incontestable alibi for Darzac.”