The words were scarcely past my lips when the door of the cab ahead flew suddenly open, and a swift something, more like a shadow than a man, darted across the moonlight, sprang upon the parapet of the bridge, and disappeared!

In an instant we were all out—­all rushing to and fro—­all shouting—­all wild with surprise and confusion.

“One man to the Pont d’Arcole!” thundered the sergeant, running along the perapet, revolver in hand.  “One to the Quai Bourbon—­one to the Pont de la Cite!  Watch up stream and down!  The moment he shows his head above water, fire!”

“But, in Heaven’s name, how did he escape?” exclaimed Mueller.

“Grand Dieu! who can tell—­unless he is the very devil?” cried the sergeant, distractedly.  “The handcuffs were on the floor, the door was open, and he was gone in a breath!  Hold!  What’s that?”

The soldier on the Pont de la Cite gave a shout and fired.  There was a splash—­a plunge—­a rush to the opposite parapet.

“There he goes!”

“Where?”

“He has dived again!”

“Look—­look yonder—­between the floating bath and the bank!”

The sergeant stood motionless, his revolver ready cocked—­the water swirled and eddied, eddied and parted—­a dark dot rose for a second to the surface!

Three shots fired at the same moment (one by the sergeant, two by the soldiers) rang sharply through the air, and were echoed with startling suddenness again and again from the buttressed walls of Notre Dame.  Ere the last echo had died away, or the last faint smoke-wreath had faded, two boats were pulling to the spot, and all the quays were alive with a fast-gathering crowd.  The sergeant beckoned to the gendarme who had come upon the box.

“Bid the boatmen drag the river just here between the two bridges,” he said, “and bring the body up to the Prefecture.”  Then, turning to Mueller and myself, “I am sorry to trouble you again, Messieurs,” he said, “but I must ask you to come back once more to the Quai des Orfevres, to depose to the facts which have just happened.”

“But is the man shot, or has he escaped?” asked a breathless bystander.

“Both,” said the sergeant, with a grim smile, replacing his revolver in his belt.  “He has escaped Toulon; but he has gone to the bottom of the Seine with something like six ounces of lead in his skull.”

CHAPTER XL

THE ENIGMA OF THE THIRD STORY.

     Who ever loved, that loved not at first sight?—­MARLOWE.