The only thing that Ebony, Violet and Alex had to worry about on their trip to London was getting lost or embarrassed. Never did they think that on a school trip they would have to fight off an army of the undead. The only thing the three friends wished for was to escape their families for a few weeks, now all they want is to go back to America where you don't have to fight for survival every day. Things get complicated when leaving London is forbidden and punishable by death.