Jim's red head was bending over the peri-telescope view-screen. "She's still thirty thousand miles away. Give her a speed of fifteen per second--she'll have to slow up to land, can't make it under forty-five minutes. By then we'll be in little pieces. It took me ten minutes to burn through the barrier when I rescued Darl, and it won't take the Mercs any longer to get at us." Darl was very sober as he looked on with narrowed eyes. Against a background of velvet black, gold spangled, the slim space-traveler showed. The sun's rays caught her, and she was a tiny silver fish in the boundless void. "Luik ye, mon, luik ye!" Angus, fairly dancing with excitement, elbowed Darl aside. "She's from Airth, richt enow!" At the nose of the oncoming flier a rapid succession of colored lights had flashed, the recognition signal that should give her safe access to the Dome. Again there was a coruscation of coded flashes. "She's a battle cruiser, what's mair!" the Scot exclaimed. * * * * * Darl sprang to the keyboard that manipulated the signal lights from the Dome's roof. "No use," he said, after a short while. "The Martian has cut off the current from the dynamos. I can't warn the ship." He made a hopeless gesture. Jim looked at him wonderingly. "Warn 'em? What for? Even if we are all dead when she reaches here, at least she'll clean up the Mercs, and retake the Dome for Earth." "Don't you see it? When the Mars man has once blasted his way in here and disposed of us, he'll be ready for the space ship. Her captain can't suspect anything wrong. He must have left Earth at the time of the ultimatum, and would easily get here before any ship could be sent out from Mars. He'll come on till he's within range of the beam-thrower, and the Martian will aim, press the trigger and the Earth ship and her crew of a half a thousand brave lads will be star-dust." "Oh God!" Jim was white-faced. "Isn't there anything we can do? Maybe if he doesn't get our all-clear signal he'll sheer off." This was clutching at straws. "Why should he? He must know how short-handed we are, and will simply think we're not on watch, or that our signal lights are out of order. Matter of fact, if he were at all suspicious he should be alternating his course right now--and he hasn't. Look." Seemingly motionless, but really splitting the ether with terrific speed, the warship was coming straight on to garrison the beleaguered post. She had never wavered from her straight course for the Dome. The little group was silent, watching the help that was coming at last, coming too late. * * * * *