Portals — Ann Christy

The world sees the portals as an invasion. For Lysa, they're an invitation.

The portals appeared without warning. Every thirteen minutes they take a thousand humans, leaving exact duplicates in their place. Now, chaos reigns and no one is sure anyone is still the person they knew. Whoever is sending the portals has destroyed human society without firing a shot.

But not everyone thinks they're a prelude to invasion. Lysa, a student far too bright for her own good, believes the portals could be something wonderful. Her burning curiosity leads her to do the unthinkable; she leaps through a portal meant for another.

What she finds is a galaxy teeming with life, worlds beyond imagining, and two terrible truths: Earth is in danger, and the portals are a one-way trip. Stranded in an alien civilization, Lysa will have to use her ingenuity to find a way home and warn Earth before it's too late.