Deep in the jungles of Central America, an archeological expedition to discover a lost city is cursed by a legendary Headless Demon. Thankfully, Miss Mallard and Willard are part of the expedition and they soon learn the lost city is not so lost. Someone has been there before them and is now trying to keep them away. In the middle of the jungle, with no more than bicycle tracks for a clue, Miss Mallard reveals the Headless Demon's true identity and a lost treasure is saved.

Willard has gone missing. He left Switzerland, against orders, in pursuit of a gold thief, and has disappeared in the Himalayas. Miss Mallard comes looking for her nephew but she finds more than she could ever have imagined: a mysterious hidden city, the yeti, a fountain of youth. All play a role in Willard's disappearance and the theft of gold he was investigating. Miss Mallard solves the mystery and ensures the safety off all her new friends, including The Abominable Snowduck of the Himalayas.

The search for extra terrestrial life takes on new dimension when it becomes clear an alien is sabotaging the International space station. Miss Mallard and Willard follow the clues right up into space where they see the alien for themselves. But seeing is not necessarily believing, and Miss Mallard knows the real saboteur wants everyone to believe aliens are responsible. Now she just has to prove it.