This is not a Test, book 2 : Please Remain Calm
Courtney Summers2015

In this gripping sequel to THIS IS NOT A TEST, Rhys and Sloane are headed for a safe haven when they get separated along the way. Rhys is determined to reunite with Sloane until he discovers people who might need him more--people who offer him the closest he'll get to everything he's lost, if they can just hold on long enough.

Rhys thinks he has what it takes to survive and find the girl he lost, but in a world overrun by the dead, there are no guarantees and the next leg of his journey will test him in unimaginable ways ...