After dozens of boats go missing along Lake Brighton, the Gravediggers decide to investigate, sensing monstrous foul play. But when they discover an antique hatchet buried in a boat's stern, their clue path leads them to their toughest foes yet - zombie Vikings! With the Brighton Boat Show fast approaching, it's up to Digger and Spade to stop the undead nordics before they pillage the town and finish building their Viking ship!