by Kenneth Oppel

First  the rain brought seeds that grew into alien plants that burrowed and strangled and fed.  Seth, Anaya, and Petra are strangely immune to the plant’s toxins and found a way to combat them,  But just as they have their first success, the rain begins again.  But our heroes aren’t able to help this time–they’ve been locked away in a government lab with other kids who are also immune.  What is their secret?  Could they be…part alien themselves?  Whose side are they on?