After the World Ends: Save (Book 4) - After The World Ends, #4

From New York Times and USA Today bestselling author Jamie Thornton. DESSA IS RUNNING OUT OF TIME. The side effects from the zombie-blocker meds have become too great to bear, and so Dessa and her friends must bring all the Project Polus children to a special government facility called Sanctuary to get them help. But when rogue soldiers attack, the group is split. Now, in order to reach Sanctuary in time, Dessa and her companions must brave the dangers of almost a hundred miles of swampy river.
Unfortunately, zombies can swim. ********AFTER THE WORLD ENDS is a new series in the same bestselling universe as ZOMBIES ARE HUMAN. New characters. New adventures. A thrilling zombie apocalypse awaits.