Scientist Artemis Masters travels with his children Curie and Nick to the Adirondacks where he has been hired by local resort owners to develop an early warning system for snowstorms, but when he becomes ill, Curie and Nick take over managing the experiment while trying to figure out why their hosts are trying to sabotage their efforts.

Mimi, Papa, Christina, and Grant travel to Tombstone, Arizona, and find themselves helping new friends, Jorge and Rosita, uncover the secret of the haunted mine.

"Christina, Grant, Mimi and Papa snowmobile into Yellowstone National Park to encounter mud pots, geysers, bison, beauty, bears, volcanic action, and a mystery of historic proportions!"--p. [4] of cover.

Christina, Grant, Mimi, and Papa travel to Wyoming's Devils Tower and climb into a "towering" mystery involving Native Americans, precocious prairie dogs, fascinating footprints, Unidentified Flying Objects, and aliens?

When they travel by train across America, Christina, Grant, Mimi, and Papa find themselves facing mysterious mishaps, spooky surprises, and treacherous tunnels.