Planet Z (Planet Z Book 1‪)‬

Twins Carlos and Jill have just lost their mother in a tragic accident. On the brink of insanity and in a desperate attempt to bring his beloved wife back from the dead, their father unwittingly transports his children to a mysterious planet instead. The twins find themselves in a place inhabited wholly by the dead ― a midway point for those waiting to pass on to the next stage ― and are suddenly embroiled in a plan to allow the dead access back to their home planet. After they get separated, a desperate struggle ensues as they try to save their world, find their mother and get back home before a madman brings about the zombie apocalypse.