Thoughts are instant things. I was crouching there behind the engine loader no more than a moment; and suddenly down the other side deck just beyond the smoking lounge, I saw a moving figure. A slight figure in dark cloak and hood--the bottoms of black and white trousers were visible. Brenda? It made my heart pound. For a second I stared as she ducked into a doorway. I was there in twenty seconds, until I saw the cloaked shadow of her going down a companion ladder into the ship's hold. Swiftly I followed. Down two eight-foot levels, and then I caught another glimpse of her as she moved into the lower passage. It was a metal catwalk with small cubbies opening from it. The ship's air-renewers, ventilating system; a cubby controlling the hull gravity-plate shifters; other mechanism rooms. She went past them, a furtive little shadow. And stopped at what seemed the door to one of the tiny pressure chambers of an exit-porte in the side of the hull. "Oh, you, Mr. Fanning? What do you want down here?" The voice in the silence so startled me that I whirled. It was Kellogg, the ship's gravity-control operator. In his shirtsleeves, pipe in hand, with a green eyeshade on his forehead, he had seen me from the door of his little cubby. "Why--" I murmured. "Just coming down to see you." I turned to join him. And suddenly a buzzer in his control room interrupted him. I stood while he answered it--an audio-tube for direct voice-transmission. "Yes, Captain Wilkes--" And then Kellogg gasped and clutched at the table beside him; then he whirled upon me, his face chalk-white. "Our radio-helio is smashed! Someone--something smashed it!" Our little _Seven Stars_ was cut off from Earth or Mars communication! Captain Wilkes had evidently decided to flash a call for help to Earth, and found that the apparatus had been smashed! But even that startling news instantly was stricken from Kellogg and me. Out in the corridor quite near us a low scream sounded! And then there was the sound of air hissing! "What the devil!" Kellogg gasped. My gun was in my hand as we ran. There was nothing in sight on the dim little catwalk. The scream had died. The air-hissing stopped. "Somebody went into the pressure-chamber!" Kellogg muttered. "What in the hell--"