“I know what you want me to say,” said Parker. “That he was sandbagged first and dead before he fell. But I don’t see it. I say he would have caught his toe in something and tripped forwards and struck his head straight away and died of that. There’s nothing impossible about it.”

“Then I’ll try again. How’s this? That same evening, Mrs. Crump, the head charwoman, picked up this onyx scarab in the passage, just beneath the iron staircase. It is, as you see, rounded and smooth and heavy for its size, which is much about that of the iron knobs on the staircase. It has, as you also see, a slight chip on one side. It belonged to the dead man, who was accustomed to carry it in his waistcoat pocket or keep it sitting on the desk beside him while he worked. What about it?”

“I should say it fell from his pocket when he fell.”

“And the chip?”

“If it wasn’t there before-”

“It wasn’t; his sister says she’s sure it wasn’t.”

“Then it got chipped in falling.”

“You think that?”

“I do.”

“I think you were meant to think that. To continue: some few days earlier, Mrs. Crump found a smooth pebble of much the same size as the scarab lying in the same passage at the foot of the iron staircase.”

“Did she?” said Parker. He uncurled himself from the window-seat and made for the decanters. “What does she say about it?”

“Says that you’d scarcely believe the queer odds and ends she finds when she’s cleaning out the office. Attributes the stone to Mr. Atkins, he having taken his seaside holiday early on account of ill-health.”

“Well,” said Parker, releasing the lever of the soda-siphon, “and why not?”

“Why not, indeed? This other pebble, which I here produce, was found by me on the roof to the lavatory. I had to shin down a pipe to get it, and ruined a pair of flannel bags.”

“Oh, yeah?”

“Okay, captain. That’s where I found it. I also found a place where the paint had been chipped off the skylight.”

“What skylight?”

“The skylight that is directly over the iron staircase. It’s one of those pointed things, like a young greenhouse, and it has windows that open all around-you know the kind I mean-which are kept open in hot weather. It was hot weather when young Dean departed this life.”

“The idea being that somebody heaved a stone at him through the skylight?”

“You said it, chief. Or, to be exact, not a stone, but the stone. Meaning the scarab.”

“And how about the other stones?”

“Practice shots. I’ve ascertained that the office is always practically empty during the lunch-hour. Nobody much ever goes on the roof, except the office-boys for their P.J.’s at 8.30 ack emma.”

“People who live in glass skylights shouldn’t throw stones. Do you mean to suggest that by chucking a small stone like this at a fellow, you’re going to crack his skull open and break his neck for him?”

“Not if you just throw it, of course. But how about a sling or a catapult?”

“Oh, in that case, you’ve only got to ask the people in the neighbouring offices if they’ve seen anybody enjoying a spot of David and Goliath exercise on Pym’s roof, and you’ve got him.”

“It’s not as simple as that. The roof’s quite a good bit higher than the roofs of the surrounding buildings, and it has a solid stone parapet all round about three feet high-to give an air of still greater magnificence, I suppose. To sling a stone through on to the iron staircase you’d have to kneel down in a special position between that skylight and the next, and you can’t be seen from anywhere-unless somebody happened to be on the staircase looking up-which nobody obviously was, except Victor Dean, poor lad. It’s safe as houses.”

“Very well, then. Find out if any member of the staff has frequently stayed in at lunch-time.”

Wimsey shook his head.

“No bon. The staff clock in every morning, but there are no special tabs kept on them at 1 o’clock. The reception clerk goes out to his lunch, and one of the elder boys takes his place at the desk, just in case any message or parcel comes in, but he’s not there necessarily every moment of the time. Then there’s the lad who hops round with Jeyes’ Fluid in a squirt, but he doesn’t go on to the roof. There’s nothing to prevent anybody from going up, say at half past twelve, and staying there till he’s done his bit of work and then simply walking out down the staircase. The lift-man, or his locum tenens, would be on duty, but you’ve only to keep on the blind side of the lift as you pass and he couldn’t possibly see you. Besides, the lift might quite well have gone down to the basement. All the bloke would have to do would just be to bide his time and walk out. There’s nothing in it. Similarly, on the day of the death. He goes through towards the lavatory, which is reached from the stairs. When the coast is clear, he ascends to the roof. He lurks there, till he sees his victim start down the iron staircase, which everybody does, fifty times a day. He whangs off his bolt and departs. Everybody is picking up the body and exclaiming over it, when in walks our friend, innocently, from the lav. It’s as simple as pie.”

“Wouldn’t it be noticed, if he was out of his own room all that time?”

“My dear old man, if you knew Pym’s! Everybody is always out of his room; if he isn’t chatting with the copy-department, or fooling round the typists, he’s in the studio, clamouring for a lay-out, or in the printing, complaining about a folder, or in the press-department, inquiring about an appropriation, or in the vouchers, demanding back numbers of something, or if he isn’t in any of those places, he’s somewhere else-slipping out for surreptitious coffee or haircuts. The word ‘alibi’ has no meaning in a place like Pym’s.”

“You’re going to have a lovely time with it all, I can see that,” said Parker. “But what sort of irregularity could possibly be going on in a place like that, which would lead to murder?”

“Now we’re coming to it. Young Dean used to tag round with the de Momerie crowd-”

Parker whistled.

“Sinning above his station in life?”

“Very much so. But you know Dian de Momerie. She gets more kick out of corrupting the bourgeois-she enjoys the wrestle with their little consciences. She’s a bad lot, that girl. I took her home last night, so I ought to know.”

“Peter!” said Lady Mary. “Quite apart from your morals, which alarm me, how did you get into that gang? I should have thought they’d as soon have taken up with Charles, here, or the Chief Commissioner.”

“Oh, I went incog. A comedy of masks. And you needn’t worry about my morals. The young woman became incapably drunk on the way home, so I pushed her inside her dinky little maisonette in Garlic Mews and tucked her up on a divan in the sitting-room to astonish her maid in the morning. Though she’s probably past being astonished. But the point is that I found out a good bit about Victor Dean.”

“Just a moment,” interrupted Parker, “did he dope?”

“Apparently not, though I’ll swear it wasn’t Dian’s fault if he didn’t. According to his sister, he was too strong-minded. Possibly he tried it once and felt so rotten that he didn’t try it again… Yes-I know what you’re thinking. If he was dopey, he might have fallen downstairs on his own account. But I don’t think that’ll work. These things have a way of coming out at post-mortems. The question was raised… no; it wasn’t that.”

“Did Dian have any opinion on the subject?”

“She said he wasn’t a sport. All the same, she seems to have kept him in tow from about the end of November to the end of April-nearly six months, and that’s a long time for Dian. I wonder what the attraction was. I suppose the whelp must have had something engaging about him.”

“Is that the sister’s story?”

“Yes; but she says that Victor ‘had great ambitions.’ I don’t quite know what she thinks he meant by that.”

“I suppose she realized that Dian was his mistress. Or wasn’t she?”