Following a successful military campaign, the
Romans conquer
most of Britain. However, one village (situated in present-day
Kent) manages to resist the invaders. Mykingdomforanos, the village's chief, knowing they will need help, assigns his best warrior, Anticlimax, to seek help from his cousin in
Gaul, after he mentions how they rely on a potion of superhuman strength to resist the Romans. Travelling by night, he reaches
Armorica, where he reunites with his cousin Asterix and explains the situation to him. Druid
Getafix, being informed of his request, agrees to supply a barrel of potion, with Asterix and
Obelix offering to help transport it to Britain. Before they leave, Asterix notices Getafix in possession of strange herbs he got from the Far East, and takes some with him. Travelling across the
English Channel, the group encounter a Roman galley, which Obelix delights in boarding, having been bored with the Roman's absence around their village. However, a Roman officer overhears them talking about their mission and returns to Britain to give warning to newly appointed governor Encyclopaedicus Britannicus. After Asterix and his friends narrowly avoid being captured by a Roman patrol searching for them, they make for the city of
Londinium and hide out at a tavern run by Dipsomaniax. Britannicus, learning they were heading for the city, guesses their likely actions and has all barrels of
beer and wine confiscated from every tavern and inn, leading to the magic potion being seized amongst them. The following day, Asterix, Obelix and Anticlimax head to the governor's palace to get the potion back. Finding the Romans have gotten drunk after being up all night taste testing the barrels, with one having had the potion by accident, they discover they can't find their barrel amongst those taken from Dipsomaniax's tavern. Although they take these barrels back, Obelix accidentally gets drunk from one of them and distracts the group into fighting a Roman patrol, allowing a thief to steal them. Asterix and Anticlimax attempt to search for the thief with little luck, before finding the Romans had razed Dipsomaniax's tavern to the ground in their absence, arresting him and Obelix, per Britannicus' orders. Learning they were imprisoned in the
Tower of Londinium, they attempt to rescue them, though fortunately Obelix, recovering from his hangover, breaks himself and Dipsomaniax from prison, reuniting with Asterix and Anticlimax. Resuming their search, Asterix, Obelix and Anticlimax eventually track down the thief to a suburb of the city. Learning he sold all the barrels, they find that the barrel of magic potion was eventually sold on to a rugby team, and seize it from them during a rugby match. However, in their escape along the
Thames, the Romans ambushes the trio, destroying the barrel and spilling its contents into the river. Although disheartened, Asterix recalls the herbs he took and decides to feign making the potion with them. The resulting brew gives a psychological boost to the rebel Britons, who promptly defeat another Roman assault with ease. Mykingdomforanos, made aware of the truth, asks for more of the herbs after declaring the brew will be their national drink. After bidding farewell to Anticlimax, the Gauls return home. During a banquet held by their village in honor of their latest victory, Asterix inquires about the herbs, to which Getafix reveals them to be called
tea. ==Characters==