How to Ride a Dragon's Storm

How to Ride a Dragon's Storm is the seventh book in the How To Train Your Dragon book series

Plot
The book begins with the normally solitary, Madguts the Murderous (head of the Murderous tribe), extending an invitation to the Hooligans and Bog-Burgulars to compete in an Intertribal Friendly Swimming Race. It's revealed victory will be awarded to the last viking to come ashore and after swearing an oath that he/she received no aid "from boat or float," was allowed to make any request of the losing chiefs. Old Wrinkly serves as a judge and before setting Hiccup off, he sets an alarm on the "ticking thing" attached to Hiccup's wrist and informs him he MUST return within 3 months, 5 days, and 6 hours. With the sounding of the horn, Hiccup and his friends rush into the water, not expecting to last long.

During the first few minutes of the competition, Madguts and his assistant, Gumboil trick Big-Boobied Bertha and Stoick into returning to shore, thereby disqualifying them and setting a new record for the fastest time back. Both are enraged but neither of them realize this is all a part of Madguts' much darker overall plan. Meanwhile, a confrontation with Snotlout and Dogsbreath leaves Fishlegs without flotation armbands as Camicazi, their dragons, and Hiccup struggle to keep both themelves and Fishlegs afloat as they drift farther from land. Horrorcow is sent back to shore for help and things go from bad to worse as they are pulled under by a mysterious creature. Their dragon captors then drop the children aboard a strange, huge boat (aptly named The American Dream 2 in honor of his Papa's ship) captained by Norbert the Nutjob and bound for America. He informs Hiccup he agreed to give Madguts shelter on his boat, ensuring he won, in exchange for Hiccup, Fishlegs, and Camicazi. Norbert reminds Hiccup of the promise to kill him if the two ever met again and takes back his father's "ticking thing" Hiccup stole. As Norbert's axe falls to the deck, Hiccup discovers Norbert can't read the ticking thing and offers to help Norbert navigate to America if he spares their lives until they arrive. Norbert reluctantly agrees and sets the children free. While on the boat, they discover many of Norbert's strange inventions including his dragon-repelling-and-keeping-the-ship-from-sinking device, a flying machine, and, upsettingly, the ship is being steered with over a hundred Wanderer slaves.

Meanwhile, back on the shores of the Murderous Mountains, Madguts is the last to return to shore, with the children presumed drowned, and wins the competition. In the grim final part of his plan, he requests both Bertha and Stoick be sacrificed to the Sky Dragons and their lands be turned over to him as revenge for Stoick's great-grandfather, Grimbeard the Ghastly sacrificing the chief of the Murderous tribe after the last swimming competition. Old Wrinkly intervenes and convinces the head judge Grimbeard stayed out at sea for over 3 months and it would only be fair to wait the same amount of time for the return of Hiccup and his friends, it's decided if the children fail to return within 3 months, 5 days, and 6 hours, Madguts will become the winner by default. The Murderous tribe imprisons Stoick and Bertha until then.

Back on the ship, Hiccup accidentally falls below deck through a hatch, where the Wanderer slaves are chained. They are about to kill him when he speaks to them in Dragonese and promises to free them if they allow him to live. They comply but give him the Slavemark so he can't forget his promise; Hiccup hides the Slavemark under his helmet because it means automatic banishment and exclusion from being chief in all viking tribes. With Stormfly and Toothless' accidental discovery of dragon nip, Hiccup formulates an escape plan, and slips the substance into the evening meal to put the entire crew to sleep. Hiccup and his friends free all of the slaves and set them afloat in the ship's life boats as the ship passes through the Northern territories. He and his friends attempt to escape with the slaves but this backfires and Hiccup unknowingly awakens an ancient slumbering Leviathorgan and barely gets back aboard the ship alive.

The three young vikings, seemingly abandoned by the Wanderers, try to come up with a new plan of escape before they reach America and certain death. They realize they have bigger problems when they discover the Leviothorgan followed them and is only kept at bay by Norbert's bizzare machine. When they are about to make landfall in America, Norbert decides he no longer needs Hiccup to navigate and attempts to kill him. As a savage storm hits the boat, Hiccup incites a rebellion onboard by claiming Norbert tries to kill him because he's a redhead and intends the same fate for all the redheads in his tribe. In the confusion of the ensuing fight, the Leviathorgan attacks the ship. While Camicazi and Fishlegs are thrown overboard, Hiccup is trapped on the ship and being chased by an enraged Norbert. Hiccup tricks Norbert into following him onto the mast and electrocuting himself by using his axe as a lightening rod; this action also kills the Leviathorgan. As Hiccup jumps from the mast, he hits his head and is saved by Fishlegs, who teaches himself to swim in the heat of the moment. Camicazi and Fishlegs put Hiccup on an over-turned table and swim as far as they can from the shore to escape any potential survivors of the Hysteric tribe.

As they are about to sucuumb to the freezing water, ships appear on the horizon and it's revealed the Wanderers returned to rescue them. Hiccup awakens and discovers they only have 24 hours to get home and will never make it by ship. The friends decide their only option is to use the flying machine they salvaged from the wreckage of The American Dream 2. Miraculously the machine works perfectly and finally crashes a few hundred yards from the shore of the Murderous Mountains, the trio make it back with two minutes to spare and are greeted with an extremely warm welcome from their tribes. Hiccup is declared the winner because he's the only one of the three (the kidnapping didn't count, but Camicazi and Fishlegs sought assistance from the Wanderer ships while Hiccup was unconscious and unaware) who didn't seek aid from float or boat. He recognizes violence repeats itself and rather than demanding Madguts be sacrificed, Hiccup requests he instead attend the next Thing dressed as a "pretty shepardess and sing love songs in front of all the tribes." The book ends with Stoick and Bertha being released from prison, both tribes celebrating victory, and Stoick showing immense pride in his son