The Clan has been searching for the treasure for centuries but Scrooge, the last McDuck, believes he can locate it thanks to an X-ray machine that can examine through the castle's walls.

During this, Scottie, the caretaker of the castle, seems to have been murdered by Sir Quackly, while Scrooge, Donald, and the Nephews find themselves trapped in a locked battlement.

The ghost is revealed to be a thief who was impersonating Scottie (who had died of old age years before) using a special spray-like formula that made him invisible, but didn't prevent his skeleton from casting a shadow.

Enraged, the nephews then trick Donald into thinking the spray is a mosquito repellent, where they then make him completely invisible save for his tail and legs.

Uncle Scrooge had been introduced in "Christmas on Bear Mountain", published in December 1947; this story was the character's return.