Too late now! He grinned his joy, went up the last flight to the roof, to find his three men in a state of mutiny, the quelling of which was not left to him. The glitter of a bayonet came through the door opening, a khaki figure slipped on to the roof, finger on trigger.

“Hands up, you!” he said, in a raucous Cockney voice.

Four pairs of hands went upward.

Manfred followed the second soldier and caught the doctor by the arm.

“I want you, my friend,” he said, and Oberzohn went obediently down the stairs.

They had to pass Gurther’s room: the door was open, and Manfred pushed his prisoner inside, as Poiccart and Leon ran up the stairs.

“The girl’s all right. The gas killed the snakes the moment they touched the floor, and Brother Washington is dealing with the live ones,” said Leon rapidly.

He shut the door quickly. The doctor was alone for the first time in his life with the three men he hated and feared.

“Oberzohn, this is the end,” said Manfred.

That queer grimace that passed for a smile flitted across the puckered face of the doctor.