Asterix and the Laurel Wreath is the eighteenth volume of the Asterix comic book series, by René Goscinny (stories) and Albert Uderzo (illustrations). It was originally serialized in Pilote issues 621-642 in 1971 and translated in to English in 1974.
To explain why they are in Rome, the story flashes back to Lutetia where Asterix, Obelix, Chief Vitalstatistix and his wife Impedimenta are on a shopping trip. The men are loaded with parcels and packages. Furthermore they are visiting Impedimenta's brother Homeopathix. Vitalstatistix dislikes Homeopathix, a rich, crass businessman who immediately shows off his wealth. Impedimenta is always reproaching Vitalstatistix for not matching this wealth or getting on with her brother. At dinner, Vitalstatistix quickly gets drunk and offers Homeopathix something money can't possibly buy: a stew seasoned with Caesar's laurel wreath. An equally drunk Obelix declares that Vitalstatistix is "ferpectly right" and volunteers himself and Asterix to fetch the wreath.
The story now returns to Rome. Asterix and Obelix see a man coming out of Caesar's palace. Discovering that he is a slave there, they decide to offer themselves as slaves and go to the slave trader Typhus, who has only the best slaves to offer and who also supplies Caesar's palace. Typhus' other slaves are a rather snobbish, arrogant lot and their attitude soon provokes the Gauls into a fight. A man, whom Asterix believes is Caesar's major-domo, is amused and offers to buy them.
However, he turns out to be Osseus Humerus, a wealthy patrician who has nothing to do with Caesar's household. The Gauls are placed under the supervision of Goldendelicius, Humerus' chief slave. Goldendelicius soon expresses his intense dislike of the two Gauls because they come from Typhus — which is a mark of distinction — and he doesn't and he's worried about his position as head slave.
Disappointed that they have not made it into the palace, Asterix and Obelix make several disruptive attempts to have Humerus give them back to Typhus; they cook a very volatile stew, which accidentally cures Humerus' heavy-drinking son Metatarsus of his constant hangovers; and disturb the sleeping family by making a lot of noise, which only inspires them to throw a wild party.
Humerus was due to go to Caesar's palace for a meeting with an official there. As a result of the party he has a bad hangover and tells the Gauls to go and tell the official that he cannot attend.
Goldendelicius is still concerned that Asterix and Obelix will take over his job, so he slips away to the palace himself and tells the guards that the Gauls are planning to kill Caesar. As a result, Asterix and Obelix are thrown into the palace cells upon arrival. Under this advantageous situation, they break out during the night and comb the palace in search of the laurel wreath but to no avail. Frustrated and tired, they return to their cell, much to the confusion of the palace guards. Asterix decides that the only option is to find Caesar himself, since the laurel wreath is usually on his head.
The next morning a lawyer comes to defend Asterix and Obelix, who are to face trial for the "attempt" on Caesar's life. It's already taken for granted that they will be found guilty and thrown to the lions in the Circus Maximus, which Caesar himself might attend. Since it is a show trial anyway, the lawyer decides to take advantage to show off his oratory skills. When the prosecutor announces that he is going to make the same speech, the defence lawyer calls for a suspension in proceedings. Anxious to be sentenced to the Circus in order to catch Caesar, it is Asterix himself who makes a passioned speech for the prosecution, outlining all the wrongdoings committed by himself and Obelix: the wrecking of Typhus' slave stand, the chaos in the Humerus household and the "plot" against Caesar. The whole audience, including Typhus and the Humeruses, is moved by this plea of guilty and the Gauls are sentenced to death in the Circus.
In the cells, they are treated to first-class meals and gifts are even sent by Typhus and Humerus.
However, as they are about to enter the arena, Asterix and Obelix learn that Caesar is actually not present, having gone off to fight pirates. Stubbornly, the Gauls refuse to go into the arena until he returns, which results in the big cats in the arena eating each other, a mass riot of the audience, and everyone (including Asterix and Obelix and the last remaining lion) getting evicted from the circus.
That night, Asterix and Obelix sleep inside a doorway, where they are spotted by a group of brigands. The latters' attempt to rob the two Gauls results in a thrashing for the bandits. Impressed, their chief offers Asterix and Obelix a place to stay in return for their participation in their raids. The next night, the gang runs into a drunk who turns out to be Metatarsus. Refusing to allow them to attack an innocent, Asterix and Obelix thrash the bandits again.
From Metatarsus the two Gauls learn that he had just been celebrating with Goldendelicius in a nearby tavern for Goldendelicius' promotion as Caesar's personal slave, and that Caesar is about to make a triumph the very next day for his victory over the pirates. Asterix and Obelix corner Goldendelicius in the tavern (where he has fallen into a drunken sleep) and coerce him to exchange Caesar's laurel wreath for one made of parsley. The next morning, just before the triumph, Asterix and Goldendelicius secretly switch wreaths.
The next day, during the triumph, Goldendelicius holds the wreath over Caesar's head, nervously worried that he'll notice that it is made of parsley. The dictator does not notice the switch, though he secretly "feels like a piece of fish".
Upon Asterix and Obelix's return, Homeopathix arrives in his brother-in-law's village in order to eat the stew with Caesar's laurel wreath. Vitalstatistix even states that a wealthy man like him would never be able to eat such a meal in his own house. Homeopathix "agrees" by sarcastically pointing out that it is overcooked and the meat in not up to the quality he expects at home. This causes Vitalstatistix to punch him sky-high in a fit of rage.