Mirrorfall (Require: Cookie, Book #1

A magical thing happened to Stef Mimosa when she was only two: she died and an angel confronted Death to bring her back.

As it turns out, her angel is really Ryan: an operative for an organization known only as the Agency. Their second meeting recruits Stef into his world, where bleeding-edge science is indistinguishable from magic and where she might just be farther out of her element than she already was in normal life.