"Both! The motive of the first crime was robbery, of the second jealousy--and perhaps a trifle of vengeance."
"I don't understand."
"It is not difficult," replied Torry with a shrug. "Listen! In some way, I can't say how--Vass became aware that Julia, at the instigation of Miss Hargone, was to meet Grent in Mortality-lane. He watched and followed, witnessed the interview, and when Grent gave the money to Julia, sprang forward in a fit of jealous rage and killed him. Then he forced Julia into the cab, and drove to the end of Northumberland-Avenue. He took her down to Cleopatra's Needle on some pretence, killed her out of revenge for her betraying him, and robbed her of the money. Then he tried to throw her body into the river, but was interrupted and fled. That is my theory, and a very nice one it is."
"It would be better," responded Darrel drily, "if it were not so full of flaws."
"Flaws!"
"Yes. You omit the Blue Mummy altogether; you make Vass decoy Julia to the Embankment without the shadow of an excuse--why you can't even invent an impossible one. Finally, you forget that the money was returned; so it is ridiculous to suppose that Vass would act so honestly after committing two crimes to gain it. Also, a nervous idiot like Vass couldn't kill two people in cold blood. He hadn't the spunk to do it."
Torry laughed at these so-called flaws, which he regarded as puerile; but out of sheer contradiction was about to contest them, when a faint and timid knock sounded on the outside door.
"Vass!" said Torry promptly. "Even in his knock I recognise his sneaking, vacillating nature. Now to try my game of bluff."
With a nod to Frank he went to the door, and shortly returned with Vass at his heels. The secretary was smartly dressed, and looked cool and composed, never thinking that his sin had found him out, and that the smiling little detective had set a trap for him into which he had walked blindly. There was something ironical in the situation.
"I got your note," said Vass, addressing Frank, when they were seated. "And I came on here at once. Has anything new been discovered?"