How to Speak Dragonese

How to Speak Dragonese is the third book in the How To Train Your Dragon book series.

Plot
In the third installment, while Hiccup and Fishlegs are out at sea learning how to board an enemy ship, they get lost only to have assistance from Toothless, because Fishlegs's dragon, Horrorcow, is asleep. They accidentally stumble upon a Roman ship. Apparently, they are planning an attack on Berk to steal all of their dragons. The Romans take Toothless, and the boys have to go back to their island. Gobber yells at them and Hiccup gets an awful report card. Hiccup cannot sleep that night without his best friend, Toothless.

In the morning, he finds a nanodragon in his coat pocket. It claims to be a 'living god' named Ziggerastica. He tells Hiccup if he calls his name, he will come if he needs help.

The boys are kidnapped by poorly dressed Romans trying to look like Bog-Burglars. They take both Hiccup and Fishlegs to the Roman ship. Hiccup meets Alvin the Treacherous (From How to Be a Pirate) and he puts them in a prison filled with locked up dragons. When inside the prison they meet a young female Bog-Burglar heir named Camicazi. The girl thinks that Hiccup and Fishlegs are Roman spies. They have a sword fight. Eventually, she finds out they aren't spies, but they are still trapped. Hiccup finds Toothless in a cage, and they are now reunited. Hiccup calls for Ziggerastica, he comes and soon flies away.

The kids and Toothless are put inside a giant arena to fight a breed of dragons called Sharkworms. Inside, Hiccup gets flung into the air and people think he is a god by this fascinating sight. They escape the ship and relase Ziggerastica along with other nanodragons who were helping Hiccup fly. They ride away in a hot air balloon back to Berk. They get attacked by a Venomous Vorpent and one of the heroes gets bitten. In the epilouge, it says the poison was put into one of them.