The Dragonstar Chronicles 2

The President and his senior advisors are responding to an extraordinary flash of light that detonated high above the Pacific Ocean just a few hours ago. An uneasy calm ensues...until a holographic message of alien origin suddenly appears in the Oval Office. Mr. Tremendous, Senior Executive Authority for Interstellar Transport, has misplaced "a very valuable piece of IT property" somewhere in Yosemite. He wants if back. Immediately. A terrifying display of Dragon Power in the sky above Washington demonstrates his awesome resolve.

The President sends a massive invasion force into the Park, hoping to find the mysterious unnamed item (and the "thief" to whom it is somehow attached), but information is scarce, time is short, and plans quickly go awry...