Sunwing (Silverwing Series #2)

Shade, a young silverwing bat in search of his father, discovers a mysterious Human-made building containing a vast forest. Could his father be there? Home to thousands of bats, the indoor forest is warm as a summer night, teeming with insect food, and free from the tyranny of the deadly owls. But Shade and his friend Marina aren't so sure this is paradise. Shade has seen Humans enter the forest and take away hundreds of sleeping bats for an unknown purpose. And where is Shade's father?