Their magic tree house takes Jack and Annie back to a monastery in medieval Ireland, where they try to retrieve a lost book while being menaced by Viking raiders.

Reluctant hero Hiccup Horrendous Haddock III must rescue his best friend, Fishlegs, from the deadly disease Vorpentitis. The only cure is rare and almost impossible to find ... a potato. But where will Hiccup find such a thing?

"A dragon rebellion is coming-filled with the meanest, nastiest dragons in the Archipelago. Razor-wings, Tongue twisters, and Vampire Ghoul deaths are attaching Vikings and seem to be seeking one soul in particular: Hiccup Horrendous Haddock the Third! Only a King can save them...and only a champion with all of the King's Lost Things can be King. In his adventures, Hiccup has collected quite a few "things" himself. But can a scrawny Viking save the...

"Hiccup is in hiding in the Murderous Mountains with the Company of the Dragonmark, but he is determined to become King of the Wilderwest by defeating the witch's Vampire Spydragons and steal back the King's Things from Alvin the Treacherous"--

"The Doomsday of Yule has arrived, and the future of dragonkind lies in the hands of one boy with nothing to show, but everything to fight for. Hiccup's quest is clear... But can he end the rebellion? Can he prove himself to be king? Can he save the dragons? The stakes have never been higher, as the very fate of the Viking world hangs in the balance!" --

To save his dragon from being banished, Hiccup must sneak into the public library and steal the Vikings' most sacred book.

Hiccup is a Viking teenager who aspires to hunt dragons, but doesn't exactly fit in with his tribe's longstanding tradition of heroic dragon slayers. His world gets turned upside down when he encounters a dragon that challenges him and his fellow Vikings to see the world from an entirely different point of view.

Now chief and ruler of Berk alongside Astrid, Hiccup has created a gloriously chaotic dragon utopia. When the sudden appearance of female Light Fury coincides with the darkest threat their village has ever faced, Hiccup and Toothless must leave the only home they've known, and journey to a hidden world thought only to exist in myth. As their true destines are revealed, dragon and rider will fight together-to the very ends of the Earth-to protect everything...

In an alternate ninth century, twelve-year-old Anya and a new friend face a Viking and a tsar to protect the water dragon that saved her life, putting her family's home at risk.

When thousands of Viking warriors descend on medieval Paris, Dak is captured and forced to work with the invaders while Sera and Riq defend the city, a situation that places them on opposing sides.