Finnley McDougall's boring schoolboy life in Seattle gets turned upside down when Great Uncle Hugh gives him a most unusual gift - a scruffy, rude, bad-tempered Scottish rock creature called Wullie who brings danger and disaster with him wherever he goes.

From French snobs in fancy hotels, rusting barges on the Seattle waterfront, abandoned coalmines and flooded quarries in the Scottish hillsides filled with bullies, gangsters, slobbering dogs and weird food Finn is drawn into an evil plot that threatens to destroy everything he loves... including Edinburgh Castle.

The only person who thinks that Finn is smart enough or brave enough to survive all this is his best friend and next door neighbor, Hadley Kobayashi, a girl who is wiser and tougher than Finn.