Rocks had already picked up the instrument Sharp had found in that box. He was studying it, looking it over. The principle on which it operated, he couldn't begin to guess, but he saw one thing that startled him enormously. He showed it to the detective. "Great Jehosophat!" Kennedy gasped. "A place for six fingers. Whoever built that damned thing had six fingers." The Lord of the Silent Death was not an extra-dimensional monster. It was a weapon that killed in utter silence. * * * * * The instrument that came out of the box from the tomb of the forgotten Sumerian King is now in Washington, in the secret vaults of the War Department. The experts are studying it, trying to fathom how it works. They have begun to get hints of the principle involved. Only hints, but something to go on. They have discovered that it kills in two ways. The first, and obvious way, is by pointing it directly at its victim. At the theatre he had sprayed the power, full on, across the audience, then across the ensemble on the stage, then as he went out the back had caught all others. The second way is worse. In Sharp's bag was found a sack of small round objects that look like marbles. All the owner of the weapon needs to do to kill an enemy is to drop one of those bits of glass in the enemy's pocket. Then he can go off several miles and start the weapon. The force it generates is concentrated in the bit of glass, and the silence is instantly generated, the bit of glass being destroyed in the process. That was the method Sharp used to kill McCumber. As they left the museum, Sharp dropped one of the bits of glass in the pocket of the old archeologist's coat. McCumber had found it, but had attached no significance to it. The experts hope that the War Department of this country will never need such a weapon. But if it does, it will have it. But the thing that plagues the experts, that frets the archeologists, that has caused Rocks Malone to tear his hair, is the fact that the weapon was designed to be used by a creature who had six fingers. Not five fingers. Six. And the archeologists are having drizzling fits trying to decide whether there was once a race of six-fingered creatures here on earth, a race that reached tremendous scientific heights, and vanished. Or was earth once visited by creatures out of space, who left a weapon behind them? Nobody knows. Possibly nobody will ever know. But Rocks Malone is preparing to leave for Asia Minor, to dig in the ruins of lost and gone civilizations, searching for another clue to the identity of the lost race. Penny is going with him.