Zombies Don't Surrender

As the final volume in the series opens, Maddy, Dane, and Stamp are still together, though barely, nestled safely inside the walls of Sentinel City, a stronghold designed to keep Zerkers out--and zombies in.
Maddy trains night and day, hoping to join Vera as a Keeper. Dane has been given Sentinel Support in the form a busty blonde named Courtney. And what of Stamp? Although Maddy's dad has worked hard to rehabilitate him after his Zerker bite, he's still not all . . . there.
When Dr. Swift inadvertently allows the zombies' archenemy, Val, to escape from Sentinel City, Maddy's world turns upside down. She and Stamp are vanished--expelled from the safety of Sentinel City, no better than common Zerkers. Dane, a Sentinel now, escapes punishment and is assigned to ensure that his old friends never return.
As Maddy and Stamp stray from the safety of Sentinel City, danger mounts . . . and not just for them. Val has taken up residence in a seaside town and enrolled in another Normal high school. To outwit her and save Seagull Shores from all-out zombie Armageddon, Maddy must face her archenemy once again.
Only this time, she's all alone...