He is Dogmatix,Obelix's dog.He his very small and is a very smart dog who starts thinking about deforestation even in that time.I mention this because Dogmatix is sad whenever a tree is felled.He can act as couriers and also hunt boars.He is the perfect dog for Obelix.
The Romans try to isolate the Gauls from the rest of the world by building a stockade around their village.Our friends Asterix and Obelix make a bet to the romans that they get past through their baricade and get all the local specialities from the surrounding places and give their prefect a feast.Our friends also meet many difficulties like a Gaulish traitor and theives.This is the very first book in which Obelix's dog Dogmatix is introduced.
The prefect of Gaul wants to give Julius Caesar a present, so he tells his men to capture a Gaul.The Romans capture Cacofonix the bard and send him away to Rome.By the time the Gauls realise that he is missing,it was too late.So our friends Asterix and Obelix board a Phoenician merchant ship and went to Rome.Meanwhile Caesar is not pleased with his gift so he decides to throw him to the lions.Our friends sign up as gladiators teach their new gladiator friends some new techniques during their training and then they save their bard. 
The Gauls wait outside the forest as only druids are allowed inside.The druids there perform amazing feats and is onlooked by all the druids and unknown to them also by a batch of goths who plan on kidnapping the best druid and make himhelp them with the invasion of rome.Our friends wait and wait but Getafix is nowhere in sight, and so they go inside the forest and find a visigoth helmet.So our friends leave for the land of the goths.They wait until they find their disguise and then surrender themselves to their so that they can meet Getafix again.Getafix is asked by a interperter on behalf of the chief can he help them or not.Getafix says no,but interperter for his own safety says yes to the chief. Unknown to the interperter the druid speaks gothic fluently and so reveals the plot to the gothic chief who throws everyone in prison and plans to kill them the next day. Meanwhile Getafix prepares the magic potion on pretext of a soup as his last wish. He gives this to the interperter who overthrows the present chief on the day of punishment.The Gauls keep on giving potion to every goth and motivates the to become the chief.This causes complete confusion and so causes confusion among the Goths which discourages them to invade Rome.Finaly the story ends with a blue sky under which a banquet is held.
All Gaul is at peace. 
The very first book written by Goscinny and Uderzo in the Asterix series is this book.The centurion of the neighbouring Roman camp is very curious about the Gaul's superhuman strenght,so he sends a spy to find out.Then after the spy returns, the centurion kidnaps the druid to learn the secret recipe of the magic potion.Asterix is worried that getafix has not returned and so he finds out that the druid is kidnapped.So,he infiltrates the Roman camp and surrenders himself.This is followed by a very hairy story!.The next set of books are
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