224 pp. CONTENTS: I. Orders; II. Settled; III. Off!; IV. The Strange Bird; V. Getting Down to Work; VI. Gissliver Gisslafsson; VII. The Mysterious Hangar; VIII. Capturing Mugger; IX. Work and Talk; X. Dave Grins; XI. In the Air; XII. Off on the Trail; XIII. In Camp; XIV. Disappointment; XV. Under Arrest; XVI. The Viking Cache; XVII. On the Rocks; XVIII. And Last.
