As he spoke he descended the steps, and, with Colin in close attendance, strode confidently toward the spot. They came to a halt in front of a small oak door, flush with the wall, and, catching hold of the handle, Marsden gave it a sharp turn. The next moment a gust of cold wind was blowing in their faces, and they were staring across the lawn in the direction of the study windows, from which a flood of yellow light streamed out into the darkness of the garden. It was the Inspector who first broke the silence. "That's clear enough as far as it goes," he observed. "The question is, Why did he open the door at one o'clock in the morning?" A possible explanation suddenly occurred to Colin. "I shouldn't wonder if he wanted to let in a little fresh air. He'd been making an experiment, and there was a horrible smell in the room when I spoke to him at the doorway." "You've got it," was Marsden's laconic answer. He pulled out an electric torch, a duplicate of the sergeant's, and allowed the light to play backward and forward over the patch of gravel outside. "I don't suppose there will be any footprints," he continued. "It's been freezing too infernally hard for that, and, in any case, we shall only do more harm than good by trampling all over the place in the dark." He switched off the torch, and closing and locking the door, put away the key in his pocket. "We'll get back now," he added, "and if you'll give me a hand I think we'll move the Professor's body into his own bedroom. When we've done that you can call down the servants." They returned to the study, where they found Humphries still examining the safe, and after the Inspector had exchanged a few words with his subordinate, he and Colin set about their task. Lifting the frail, bloodstained figure between them, they carried it slowly up the staircase as far as the first landing. The Professor's room was situated right at the end of the corridor, a large, sparsely furnished apartment with an old-fashioned four-poster in the farther corner. They laid their burden on the bed, and Marsden stood up, cap in hand, while Colin sponged away the blood and covered over the body with a clean sheet. "It's a wretched sort of ending to a life like his," said the detective, with an unexpected touch of feeling. "One of the greatest scholars in the world, so they tell me; and look at him now--knocked on the head and done for, just like any common drunk in a street fight!" He paused. "I'm not a rich man," he added, "but I'd give a couple of months' pay to put a rope round the neck of the party who did this." He walked to the door, and, replacing his cap, glanced up at the landing above.