At twilight, the in-between time, anything can happen, and magic is anywhere.

As one perfect summer day fades to twilight, Bat and Mr. Byrd both land, quite unexpectedly, on the same branch of the same red maple tree at the same time, and this story begins ...

Enchanted at their unlikely meeting, Bat and Mr. Byrd visit their tree branch together at twilight all summer long, during that slim grass-blade of time in which they are both awake. Soon, they realize they are more alike than different, and friendship takes many forms. Together, they discover the danger of cats, the beauty of fireflies, the meaning of loss, love, fun, joy, family, and more. With autumn comes change for these unlikely summer friends, and for Mr. Byrd, it brings the sweetest song of all.