Claudius introduces himself and speaks about his visit to Sibyl and her prophesy.
Claudius introduces his father, Augustus and Livia.
Claudius becomes a priest of Mars, and we learn about what Livia and Augustus think of Claudius through their letters.
Postumus is set up and banished to Planasia
Germanicus puts down a German revolt, and Julilla is banished - ostensibly for adultery, but also because she coudl potentially bear an heir to Augustus.
Germanicus finds out the truth about Postumus, tells Augustus, who is poisoned.
Augustus dies, and Tiberius becomes Emperor
Germanicus handles a mutiny by the Balkan forces.
Tiberus's rule and his attempts to break the cipher
From Chapters 11-17: A mutiny arises because of poor conditions of the troops. Germanicus puts it down, but his relationship with Tiberius deteriorates.
After some revelations, Augustus seems ready to reconcile with Postumus but dies suddenly. Tiberus suceeds Augustus, but remains under Livia's thumb.
Livia consolidates her position. Claudius becomes financially poorer (helping Germanicus).
Claudius connects with Postumus, who reveals himself and is killed.
Germanicus fights the Germans
Germanicus incurs Tiberus's wrath and eventually dies under mysterious circumstances.
Piso, who opposed Germanicus dies
Sejanus becomes a close confidante of the Emperor, and instigates Tiberius to go against Castor. Castor dies (likely of poisoning).
Claudius meets Urgulanilla at Plautius' (his brother-in-law's) home. That night, his new wife Apronia is killed in mysterious circumstances.
The relationship between Tiberius and Livia deteriorates
Claudius has dinner with Livia where he is told Caligula will become Emperor, and the Claudius will not be killed. Livia makes him take an oath to make her a God.
She explains:
I quite agree about the ignorant rabble. It's not so much my fame on earth that I'm thinking about as the position I am to occupy in Heaven. I have done many impious things - no great ruler can do otherwise. I have put the good of the Empire before all human considerations. To keep the Empire free from factions I have had to commit many crimes …. And what is the proper reward for a ruler who commits such crimes for the good of his subjects? The proper reward, obviously is to be defied.
Sejanus offends Tiberius by asking for Livilla's hand in marriage. This is start of his downfall. Livia dies and Tiberius inherits her fortune, keeping even those parts that were due to others.
Tiberius becomes even more unrestrained after Livia's death, getting rid of Agrippina, Drusus, Gallus and Livilla. He uses Caligula to remove Sejanus who is killed on orders of the senate.
Tiberius is killed by Marco and Caligula. Caligula becomes Emperor.
Caligula as emperor. Initially welcomed (after Tiberius' rule, and as son of Germanicus). He is a profiglate spender, soon emptying out the royal coffers. He then finds ways to get money from the rich and powerful, eventually gaining many enemies.
He also goes ?mad, and sees himself as a God, equal to the other Gods. Along the way, he rids himself of many enemies, including Marco, who initially helped him get into power. Many family members, including his mother are also directly or indirectly killed by him. Claudius survives by his wit and perceived lack of threat to Caligula.
Caligula marries Messalina to Claudius, who leaves Calpurnia.
Finally, Caligula is killed in a plot by Cassius Chaerea, who is in turn killed by Caligula's German bodyguards. In the chaos, Claudius is made emperor, and the book ends here.
Graves, R. (1978). I, Claudius: From the autobiography of Tiberius Claudius, Emperor of the Romans, born 10 B.C., murdered and deified A.D. 54. Penguin Books.