ZC One : Zombie Castle Series Book 1(Zombie Castle‪)‬

It was intended to eradicate the common cold; instead it eradicated most of the human race. A genetically modified virus killer mutates, transforming everyone it infects into zombies. As it rapidly spreads across the globe, small groups of survivors battle to stay alive and escape the growing hordes of flesh eaters. Tom, Becky and their two children are on a family holiday when the virus hits. Follow them as they try to fight their way to safety, gathering others along the way.
They soon realise that their best chance of survival will be to reach an ancient symbol of power and strength. Their future and safety lie behind a castle's walls. Together they must undertake a daunting one-hundred-mile journey. Will they make it?