Bending over the plan was a tall, burly man, dressed in the uniform of a British infantry officer. His face was in darkness, and whether young or middle-aged Ralph was unable to determine. On the floor by the side of the suspect lay a folded garment--a cloak apparently--and a German army revolver; while to keep the edges of the plan from being disturbed by the wind the man had made use of four clips of cartridges as weights. By the brass material of the clips Ralph knew that they were not British but German. "Cool cheek," thought Setley. "Quite enough evidence to place him in front of a firing party. He looks a tough customer, too." Presently Danvers crawled up and also took stock of the suspect. The two subalterns glanced at each other meaningly and nodded. Then, bounding swiftly and agilely through the gap in the wall, they threw themselves upon their quarry. The improvised table flew one way; the spy, in the grip of his assailants, the other. The plan coiled up and rolled across the rough floor until it quivered against a projecting slab of stone. The lamp, still alight, slipped to the ground, its rays directed skywards like a miniature searchlight. The fellow put up a tough fight. More than once he shook off his attackers, but was unable to regain his feet and follow up the advantage. He fought cleanly. He did not bite or kick--which was remarkable for a Hun--but used his fists with good effect, as Danvers had cause to know. At length the two chums gained the mastery, although at the end of the struggle they were almost played out. "Now what's to be done?" gasped Ralph, when the suspect was securely bound--wrists and ankles--by means of handkerchiefs and the man's own revolver lanyard. "If we've got to bring him out of this we'll have trouble. He's a lump of a chap." "Get a man to mount guard over him until we can fetch the piquet," decided Danvers, wiping the perspiration from his forehead. "By Jove! My nose feels as big as a turnip." "It's certainly swelling some," remarked Setley, surveying his chum's features by the aid of the captured electric lamp. "All right; you stand by and I'll bring a Tommy back to look after the blighter." In less than twenty minutes Ralph returned, accompanied by a corporal of the Tank section whom he had met on the road. "I've been trying to question the chap," reported Danvers. "Tried him in German. Perhaps my rendering was so atrocious that he couldn't understand, or else he's sullen. He tried to wriggle while you were away, but he seems to be lashed up tight enough." "Mount guard over him, corporal," ordered Ralph. "If he tries any of his capers prod him in the stomach with your bayonet. I don't think that would be bringing His Majesty's uniform into contempt. We'll take that revolver and the map with us as evidence." Leaving the corporal furtively eyeing his charge, like a terrier watching a rat, the two subalterns hurried back to the camp.