Without a word, but with a heart full of gratitude, Dave Darrin snatched out from its wrapping the effigy of a male human head. It was done in wax, with human hair on the head. Dave Darrin neatly fitted this at the top of the outlines of a figure under the bed clothing. Under the full light the doughface looked ghostly. In a dimmer light it would do very well. "Thank you a thousand times, fellows," trembled Dave Darrin. "Now hustle to your own quarters before the first stroke of taps sounds." The two useful visitors were gone like a flash. Ere they had quite closed the door, Dave Darrin was removing his own uniform and hanging up trousers and blouse. Next off came the underclothing and on went pajamas. Just then taps sounded. Out went the electric light, turned off at the master switch. Dave Darrin dived under the bed clothes on his own cot and tried to still the beating of his own heart. Two minutes later a brisk step sounded on the corridor of the "deck." Door after door was opened and closed. Then the door to Dave's room swung open, and a discipline officer and a midshipman looked into the room. "All in?" the midshipman called. A light snore from Dave Darrin's throat answered. In his left hand the discipline officer carried an electric pocket light. A pressure of a button would supply a beam of electric light that would explore the bed of either midshipman supposed to be in this room. But the officer saw Midshipman Darrin plainly enough, thanks to beams of light from the corridor. Over in the opposite alcove the discipline officer made out, more vaguely, the lay figure and the doughface intended to represent Midshipman Dan Dalzell. "Both in. Darrin and Dalzell never give us any trouble, at any rate," thought the discipline officer to himself, then closed the door, and his footsteps sounded further down the corridor. "Oh, Danny boy, I wish I had you here right at this minute!" muttered Dave Darrin vengefully. "Maybe I wouldn't whang your head off for the fright that you've given me! I'll wager half of my hairs have turned gray in the last minute!" However, Midshipman Dan Dalzell was not there, as Darrin knew to his own consternation. Dave did not go to sleep. Well enough he knew that he was on duty indefinitely through the hours until Dan should return. If Midshipman Darrin fell into a doze this night he would be as bad as any sentry falling asleep on any other post. So Darrin lay there and fidgeted. Twenty times he tried to solve, in his own mind, the riddle of why Dalzell should be away, and where he was. But it was a hopeless puzzle.