Time of Ruin - Ash and Ruin Trilogy, #2

The world has ended, and hope is the most dangerous thing left. Battered and bruised after barely escaping San Francisco with their lives, Kat, Dylan, and Blue press north - desperate to reach the possibility of a new home. But strange, monstrous ravens are tracking the remaining survivors, food is becoming scarce, gasoline is running short, and people are becoming suicidal, making survival almost impossible.
And the Pestas are growing bolder. Somehow, their numbers are growing. The further north they go, the harder it becomes to ignore the signs that they've made a fatal mistake. Kat must face the impossible truth that there is no escape, there is no safe haven, and their worst nightmares don't come close to their new reality.