"I'm not sure that it was," Blake said bleakly.
Tarratona looked at him sharply. "You mean there is someone else?"
Blake nodded. "There must be. And we've got to find out who before-" He broke off hesitating.
Captain Tarratona said tiredly: "Seсor Blake - you make speak freely. It is no secret to me that the present government is about to be swept from power. Revolutions come and revolutions go… but Tarratona always stays. No-one can run this country without me; therefore I bow willingly to the inevitability of progress. In any case, the country is due for a cleaning up. Revolutions are always invigorating."
Blake smiled thinly. He had no intention of divulging any confidences to the police chief. But for the moment their interests coincided.
Blake said: "I'm not sure who is controlling the Soviet network here - but I'm pretty sure I know where I can find out…"
"My car is waiting outside," Tarratona said suavely.
"It's going to take more than a car," Blake said grimly. "We've got to get to the research ship, Gorgon - and we haven't a moment to lose."
A high-speed police lauch took Blake and Tarratona on the second lap of their journey to Professor Hoddard Curtis's Gorgon.
In the bright, sharp morning sun the sea was a molten silver. The waves slapped viciously against the side of the launch, for it was a rough sea despite the heat, and a strong breeze was blowing.
Curtis himself met them as they climbed the ladder and reached the deck. The salvage operation was under way.
Hanging from the derricks on the opposite side of the ship, the bathysphere swung in its cradle like a great egg - the spawn of the monster like-ship.
The sphere was just being swung onto the deck.
Crew-men sweated with hawsers to secure it as the winches lowered it on to a cleared space.
Curtis nodded to his two guests to approach. "Don't go too close," he warned. "I'm going to have to use this." He indicated an oxy-acetylene welding kit which was being wheeled up by the mate. At the same time he donned a pair of goggles, explaining: "The sphere can only be opened from the inside. We built it that was as a safety precaution."
A moment later the torch was flaring incandescently in the young professor's hands as he went to work on the bathysphere's hatch.
It took several minutes before the door swung inwards, but finally it yielded.
The young biologist switched off the torch and stared into the murky confines of the sphere. He shuddered and looked away. His face was pale. "Worse than ever," he gulped. "The eels have had a pretty good meal… it's ugly…"
Blake and Tarratona moved forward. Blake was there first. He peered into the sphere. He had to fight down a surge of nausea at what he saw. It was gruesome. The corpse inside was unrecognisable. But the knife in the back was plain to see. The man had been murdered all right.
Then Blake saw something else. Something which set his mind thinking swiftly - until suddenly he realised what it was. And then, at last, the answer to all his questions began to click into place. He knew how the murder had been committed!
It took the best part of twenty minutes to empty the complete contents of the bathysphere on to the deck. By the time Curtis had completed an initial check of all the equipment, the spectators had been joined by the two FBI men, Navarro and Kellaher.
There was a grim silence as they all gazed at the dead body.
Curtis turned to Blake: "Well, Mr. Blake… You wanted to be here to identify the corpse. Can you make anything of it? Are you satisfied this is Harben?"
"I'm satisfied," Blake said quietly, "that this isn't Harben."
"Whatssat?" Lieutenant Navarro suddenly turned a pair of fierce eyes on the detective.
"I said," Blake repeated quietly, "it is not Harben."
"Not Harben?" demanded Kellaher. "What do you mean, not Harben?"
Blake said grimly: "Was there ever any reason to assume it was Harben? When this bathysphere went down there were two men aboard. Only one body has been recovered and as we can all see, it's unrecognisable. Why should be assume it belongs to one and not the other?"
"For one very good reason," interrupted the American Professor. "Harben was the one we heard screaming out for help just before the bathysphere broke loose - at more than seven hundred feet."
Blake nodded. "And that's precisely what tells me you've picked the wrong man. Professor, take a look at all the equipment. Are you satisfied that it's all here?"
"It's all here," Curtis said firmly without looking.
"Very well," said Blake. "Consider this: when the impossible has been eliminated, what remains must be the truth, agreed?"
Curtis nodded.
"We all know that no-one could have left the bathysphere at seven hundred feet," said Blake.
"Check," said the biologist. "At that pressure no-one could open the hatch."
"And even if they could, they'd die as soon as they did?"
"Yes."
"Very well, then it follows inevitably that the man who left the bathysphere must have done so much earlier - at not more than say fifty feet?"
Curtis frowned. "True… with an aqualung it could be done…"
"Then that's what must have happened," Blake said flatly.
The FBI man, Kellaher, interrupted with an exasperated snarclass="underline" "If the killer left the bathysphere at fifty feet, how could he have killed the other guy at seven hundred?"
Blake looked at him calmly. "He couldn't, could he? So that's one possibility eliminated. He must have killed his victim before reaching fifty feet."
Curtis looked at Blake with a baleful glare. "We're going around in circles! If this guy was dead at fifty feet. how come he was heard screaming at seven hundred?"
Blake said patiently: "Once again, the answer is he couldn't have been. Therefore he wasn't."
"The mate was on the radiophone!" snapped Curtis. "He heard Harben screaming when the bathysphere was at seven hundred feet!"
Blake nodded patiently. "And this proves what I've been saying all along: Harben's screams were heard after the murder had been committed - therefore Harben could not have been the murdered man - so by a process of elimination he must have been the killer."
"Now wait a minute-" Curtis began to get angry.
Blake cut him short. "Professor - take another look at the equipment. You say it's all here?"
"It's all here!" snapped Curtis.
"And if you look carefully," Blake insisted, "I think you'll see something that shouldn't be there."
Curtis frowned suddenly. His gaze flicked across the deck. It began scanning the piles of equipment. And suddenly, sharply, he let out an exclamation.
"I thought so!" Blake strode grimly across to the object and picked it up.
It was a small, battery-powered tape recorder. "What the mate heard on the radiophone," Blake said grimly, "was not a man at all - it was this. When the tape is dryed out and played back you'll be able to here the spine-chilling commentary designed to simulate the dying agony of a man being consumed by an unknown sea monster. All it need to complete the crime was a small charge of explosives to cut the sphere adrift - to sink it to the ocean bed and destroy all the evidence."
Blake paused, eyeing the listeners bleakly.
"The tape recording was made by the murderer long before the sphere sank - and played back after the murder had been committed. Since the voice was identified by the mate as that of Harben, it follows simply and clearly that Harben was the killer."
There was a stunned silence before Curtis demanded: "Then who's this?" He pointed at the mutilated corpse.
"This is a man called Linwood - whose real name is Peter Sellingham."
Curtis looked dazed. "But why?" he demanded fiercely. "Why did Harben have to kill him?"