Follows the further adventures and misadventures of Hiccup Horrendous Haddock the Third as his Viking training continues and his father leads a stranger and the Hairy Hooligans to the Isle of Skullions in search of a pirate's treasure.

"The Kidd children--including twelve-year-old twins Rebecca and Bickford--follow mysterious clues that take them from China to Germany, in the hopes of finding their missing father and the treasure that will finally free their kidnapped mother"--

"Following clues left by their missing father, twelve-year-old twins Bickford and Rebecca Kidd sail from the Caribbean to New York City with their siblings to finish the dangerous quest of their world-famous treasure-hunting parents"--Provided by publisher.

"While the Thea Sisters are on a tropical vacation in the Bahamas, they stumble upon an old pirate map. It's related to a local legend. Could it lead to treasure? The five mice venture onto the sparkling Caribbean Sea to follow the map--but someone else is trying to find the treasure first"--Page 4 of cover.

"It was 1798 when the Morningstarr twins arrived in New York with a vision for a magnificent city: towering skyscrapers, dazzling machines, and winding train lines, all running on technology no one had ever seen before. Fifty-seven years later, the enigmatic architects disappeared, leaving behind for the people of New York the Old York Cipher -- a puzzle laid into the shining city they constructed, at the end of which was promised a treasure beyond...

Young mouse Calib Christopher is finally a squire to the Knights of the Round Table, but there is no time to celebrate because his best friend, Cecily, and Merlin's magical treasure are in the clutches of the evil Saxons.

The discovery of an old map by his sister, Thea, leads Geronimo and his family to search for buried treasure on a faraway island.

Paulina and the Thea Sisters journey to Peru to find their missing archaeologist friend, but as they ascend the Andes Mountains, the sisters find clues that lead them to a mysterious hidden city.

"Twelve-year-old twins Bickford and Rebecca Kidd and their two older siblings travel to Africa to track down priceless artifacts that will keep the family's treasure hunting business afloat long enough to rescue their kidnapped mother--and possibly find their missing father"--Provided by publisher.