The Cambridge Latin Course (CLC) is a series of textbooks published by Cambridge University Press, used to teach Latin to secondary school students. First published in 1970, the series is now[when?] in its fifth edition, and has sold over 3.5 million copies. It has reached high status in the UK, being the most successful Latin course in the country and used by 85% of Latin-teaching schools.
The course consists of a series of chapters, each of which includes stories in Latin as well as vocabulary and grammar explained in English. There is a short history section at the end of each chapter to provide context on Ancient Rome.
The first story "Cerberus" begins:
Caecilius est in horto. Caecilius in horto sedet. servus est in atrio. servus in atrio laborat.
which means, in English:
Caecilius is in the garden. Caecilius is sitting in the garden. The slave is in the atrium. The slave is working in the atrium.
The book tells the adventures of Caecilius, a banker and paterfamilias in Pompeii from the reign of Nero to that of Vespasian. Sometimes the book deviates, to talk about Caecilius's two slaves, Grumio and Clemens, and their frequent humorous mishaps. The book also discusses Metella (Caecilius's wife) and her slave Melissa. The book ends when Mount Vesuvius erupts, and Caecilius is killed in Pompeii. However, the book leaves the reader wondering whether Caecilius' son, Quintus, survived, as indeed he did, along with the slave, Clemens. Cerberus is Caecilius' guard dog; he sits by his master as the volcano erupts. The beginning of the book is very simple, but each stage develops more complicated grammar and vocabulary. This book introduces the nominative, dative and accusative cases and different verb tenses including present, perfect and imperfect. 
The beginning of the second book is set in Roman Britain near Fishbourne Roman Palace under Agricola, where Quintus meets Salvius and King Cogidubnus, who are historical figures. The book starts by introducing a new family, a Roman aristocrat, Salvius, who is a successful lawyer and senator in Rome. His family includes his wife, Rufilla, and many slaves, some of whom are Britons, others foreign. In the second half of the book, Quintus tells King Cogidubnus about his journey to Alexandria, where he met Barbillus, a friend of his father. Barbillus later dies of a wound during a hunting trip, and tells Quintus to find his son Rufus, who lives in Britain, thus explaining the reason for Quintus' visit.
The third book picks up in the Roman province of Britain, in the city of Aquae Sulis (Bath) in particular. Cogidubnus falls ill and goes to the baths at Aquae Sulis, and Salvius, seeing his chance, hatches a plot with the baths' owner, Lucius Marcius Memor, to kill him. Quintus foils the plan, much to Salvius' dismay. He also finds Barbillus' son Rufus and gives him a message. When Cogidubnus eventually dies in captivity, Salvius writes a false will for him. A continuous narrative throughout the book also includes Modestus and Strythio, two bumbling Romans in the military.
In the fourth textbook, the setting moves to Rome, a few years after the events in Britain. Quintus is absent, and the main characters are Salvius, his ally Haterius, and several other Roman aristocrats, as well as some ordinary citizens. Salvius coordinates the death of Paris, a famous pantomime actor, and exiles Domitia, the emperor's wife, whose affair with Paris was exposed.
The book is set in Rome, after Agricola has successfully conquered Scotland. Various acquaintances of the emperor, including Glabrio, an advisor to the emperor, are introduced, as well as the emperor himself. Glabrio accuses Salvius of the forgery of Cogidubnus' will, while Domitia accuses him of plotting her exile. Quintus is present at Salvius' trial. Salvius is convicted and sentenced to five years of exile. In the remaining chapters, the writings of various poets and historical figures replace the narrative.
To suit the American format, books III and IV were combined.
Caecilius is the star of the first book. Caecilius is a banker who lives in Pompeii. When the volcano Mt. Vesuvius erupts near Pompeii, Caecilius returns to save his family. A wall falls on him in his house, and he dies.
The son of Lucius Caecilius Iucundus and Metella, Quintus is the main character of Cambridge Latin. He escapes Pompeii and in the second book goes to Alexandria, Egypt, where he is assigned to find the dying Barbillus' son Rufus. In the third book he finds Rufus, but also becomes entangled in a plot against King Cogidubnus. Quintus appears once more in the final book, where he is present for the trial of Salvius.
Gaius Salvius Liberalis, a distant relative of Quintus, first appears in the second book. He is a cruel man who is not capable of loving anything besides making others suffer. In the third book, it is revealed that he is conspiring against King Cogidubnus. In the fourth book, he becomes part of yet another conspiracy, which is no surprise, to exile the philandering Domitia and murder her lover Paris. In the final book, he is put on trial for his crimes and sentenced to five years of exile.
Cogidubnus is a client king of Britain. First appearing in the second book, he becomes a close friend of Quintus. Cogidubnus becomes ill, and it is revealed that his advisor, Salvius, is trying to murder him. Although the conspiracy fails, Cogidubnus dies in captivity of his illness. Salvius attributed his terrible actions to the fact that he could no longer feel any feelings.
Belimicus is the chieftain of the Cantiaci tribe who first appears in the second book. Throughout the books he is insanely jealous of Dumnorix, the chieftain of the Regnenses. (Dumnorix is later killed when he attempts to seek help from the governor of Britain, Agricola.) He helps Salvius in his plot to kill Cogidubnus, but begins to rebel against Salvius's authority, as he feels he deserves the kingship. Belimicus is murdered by Salvius with poison.
Haterius is a rich client and friend of Salvius who appears first in the fourth book. He constructs the arch of Titus for Domitian. He appears again, briefly, in the fifth book, in which he follows Salvius into exile.
Emperor Domitian first appears in the fourth book, briefly, although he had been mentioned several times before. Domitian is the one whom Salvius takes orders from. Although Domitian instigated the crimes, Salvius does not implicate the emperor in order to save his son.
Erik Robinson has criticized the portrayal of slavery, with no indication that a slave like Grumio would have been subject to arbitrary violence.
The popularity of the Cambridge Latin Course is such that the series has been indirectly referenced in television. The ancillary characters Caecilius, Metella and Quintus in the Doctor Who episode "The Fires of Pompeii" are loosely based on those from the Cambridge Latin Course. In the opening episode of series four of Being Human the "Vampire Recorder" blurts out words from Book One of the Cambridge Latin Course, ("Caecilius est in horto!") as part of the general nonsense he is chanting whilst pretending to perform a sacrificial ceremony.
Grumio is the name of the slave in the popular TV series Plebs.