The Android's Dream — John Scalzi

SAVING THE PLANET, ONE SHEEP AT A TIME

A human diplomat kills his alien counterpart. Earth is on the verge of war with a vastly superior alien race. A lone man races against time and a host of enemies to find the one object that can save our planet and our people from alien enslavement ... a sheep.

Yes, you read that right. Welcome to The Android's Dream.

For Harry Creek, it's a nightmare. All he wants is to do his uncomplicated mid-level diplomatic job with Earth's State Department. But his skills and past training get him tapped to save the planet-- and to protect pet store owner Robin Baker, whose own past holds the key to the whereabouts of that lost sheep. Doing both will take Harry from lava-strewn battlefields to alien halls of power.

All in a day's work. Maybe it's time for a raise.