Simon ran over its smooth surface with an expertly pessimistic eye. The lid fitted down so perfectly that it required the perspicacity of a lynx to spot the join at all. The edge of a razor couldn't have sidled into that emaciated fissure—much less the claw of the finest jemmy ever made. The only notable break that occurred anywhere in that gleaming case-hardened rhomboid was the small square panel in one side where the combination lock showed narrow segments of its four milled and lettered chrome-steel wheels—and even those were matched and balanced into their aperture so infrangibly that a bacillus on hunger strike would have felt cramped between them.
"Can you open it?" asked Monty; and the Saint shook his head.
"Not with anything in my outfit. The bloke who made this sardine can knew his job."
He snapped open one of his valises, and produced a bulging canvas tool-kit which he spread out on the bed. He slid out a small knife-bladed file, tested it speculatively on his thumb, and discarded it. In its place he selected a black vulcanized rubber flask. With a short rod of the same material he carefully deposited a drop of straw-coloured liquid on one of the links of the chain, while Monty watched him curiously.
"Quieter and easier," explained the Saint, replacing the flask in his holdall. "Hydrofluoric acid—the hungriest liquor known to chemistry. Eats practically anything."
Monty raised his eyebrows.
"Wouldn't it eat through the sardine can?"
"Not in twenty years. They've got the measure of these gravies now, where they build their strong-boxes. But the chain didn't come from the same factory. Which is just as well for us. I can't help feeling it would have been darned embarrassing to have to wade through life with a strong-box permanently attached to the bargain basement of a morgue. It's not hygienic."
He lighted a cigarette and paced the room thoughtfully for a few moments. On one of his rounds he stopped to open the communicating door wide, and stood there listening for a second. Then he went on.
"One or two things are getting clearer," he said. "As I see it, the key to the whole shemozzle is inside that there sardine can. The warriors who tried to heave Stanislaus into the river wanted it, and it's also one of the three possible reasons for the present litter of dead bodies. Stanislaus was bumped, either (a) because he had the can, (b) because he might have made a noise, (c) because he might have squealed—or for a combination of all three reasons. The man who knifed him tried to grab the contents of the attaché case and was flummoxed by the sardine can within. Not having with him any means of opening it or separating it from Stanislaus, he returned rapidly to the tall timber. And one detail you can shunt right out of your minds is any idea that the contents of the said can are respectable enough to be mentioned in law-abiding circles anywhere."
"Bank messengers have been known to carry bags chained to their wrists," Monty advanced temperately.
"Yeah." Simon was withering. "At half-past two in the morning, the streets are stiff with 'em. Diplomatic messengers have the same habits. They're recruited from the runts of the earth; and one of their qualifications is to be so nitwitted they don't know a friend when they see one. When they're attacked by howling mobs of hoodlums, they never let out a single cry for help—they flop about in the thickest part of the uproar and never try to get saved. Stanislaus must have been an ambassador!"
Monty nodded composedly.
"I know what you mean," he said. "He must have been a crook."
The Saint laughed and turned back to the bed. After one appraising scrutiny of the link on which he had placed his drop of acid, he twisted the chain round his hand and broke it like a piece of string.
With the steel box weighing freely in his hand, he lounged against a chest of drawers; and once again he looked across at Monty Hayward with that mocking half smile on his lips.
"You hit the mark in once, old lad," he said softly. "Stanislaus was a crook. And who bumped him off?"
Monty deliberated.
"Well—presumably it was one of the birds we threw into the river. A rival gang."
Simon shook his head.
"If it was, he dried himself quickly enough. There isn't one damp spot on the carpet or the bed, except for Stanislaus's gore. No—we can rule that out. It was a rival gang, all right, but a bunch that we haven't yet had the pleasure of meeting. Their representative was obviously on the set the whole time, unbeknownst, only the Water Babies forestalled him. But who were the Water Babies?"
"Do you know?"
"Yes," said the Saint quietly. "I think I know."
Mechanically Patricia Holm took a cigarette from her case and lighted it. She, who knew the Saint better than anyone else living, saw clearly through the deceiving quietness of his voice—straight through to the glinting undercarry of irrepressible mirth that weaved beneath. She caught his eye and read his secret in it before he spoke.
"They were policemen," said the Saint.
The words flicked through the room like a wisk of rapturous lightning, leaving the air prickling with suspense. Monty froze up as though his eardrums had been stunned.
"What?" he demanded. "Do you mean——"
"I do." The Saint was laughing—a wild billow of helpless jubilation that smashed the suspense like dynamite. He flung out his arms shakily. "That's just it, boys and girls—I do! I mean no more and nothing less. Oh, friends, Romans, countrymen—roll up and sign along the dotted line: the goods have been delivered C. O. D.!"
"But are you sure?"
Simon slammed the strong-box on the chest of drawers.
"What else could they have been? Stanislaus never shouted for help because he knew he wouldn't get it. I thought that was eccentric right from the start, but you can't hold up a first-class rough-house while you chew the cud over its eccentric features. And then, when Stanislaus gave me the air, I knew I was right. Don't you remember what he said? 'Ich will gar nichts sagen'—the conversational gambit of every arrested crook since the beginning of time, literally translated: 'I'm saying nothing.' But what a mouthful that was!"
Monty Hayward blinked.
"Are you telling me," he said, "that all the time I've been risking my neck to save some anaemic little squirt from being beaten up ,by three hairy toughs, and then cheerfully heaving the three toughs into the river—I've actually been saving a nasty little crook from being arrested, and helping you to murder three respectable detectives?"
"Monty, old turbot, you have so." Once more the Saint bowed weakly before the storm. "Oh, sacred thousand Camemberts—stand by and fill your ears with this! . . . And you started it! You lugged me into the regatta. You led these timid feet into the mire of sin. And here we are, with the police after us, and Stanislaus's pals after us, and the birds who bumped Stanislaus off after us, and a genuine corpse on the buffet, and an unopenable can of unclaimed boodle on the how's-your-father—and I was trying to be good!"
Monty put down his glass and rose phlegmatically. He was a man in whom the Saint had never in his life seen any signs of serious flustennent, but just then he seemed as dose to the verge of demonstration as he was ever likely to be.