The zombie outbreak plays out how you'd expect. Zombies, death, military, repeat. Until the whole area is quarantined
But sometime later, a squad is sent in to investigate the infection and they find a pair of zombies hand cuffed together.
At first you would they were just regular zombies, but it turns out that they're still alive. The squad captures them and brings them in for further testing.
Later our unfortunate protagonists will have to deal with a sudden malfunction, desperate survivors, secret societies, and maybe even a conspiracy.