A very paranoid old Claudius, emperor of Rome, nears the end of his life commences to write his family's history. The Sybil had forseen that his story will be found in 1900 years (now). The memoir begins before his birth, during the rule of Augustus. Augustus is married to the beautiful treacherous Livia. Livia tries to get rid of anyone blocking her plot to have her son (from an early marriage), Tiberius, inherit Augustus throne. Tiberius must marry Julia, Augustus daughter. Livia first step is to poison Marcellus, Julias husband. Rome is in caos and Augustus begs Agrippa to return. Unforntunately, for Livia, Agrippas price for returning is to wed Julia.

Ten years has past. Finally, Agrippas favors is not needed any more, and Livia poisons him. Livia forces Tiberius to divorce his wife and marry Julia. Unfortunately the marriage is quite bad. Tiberius' favourite brother, Drusus, gets injured in battle and dies in care of Livia's doctor (probably poisoned by Livia). Drusus son Claudius has just been born when his father dies. Tiberius quarrels with his wife, goes on a rampage and gets banished from Rome. Only Julia's (and Agrippas) sons pleases Augustus.

Determine to see Tiberius, her exciled son, become emperor, Livia uses blackmail and murder to eliminate rivals and end his banishment. Livia, one by one, kills off Julia's son, starting with Gaius. Rome is forseen to fall and Claudius destined to protect it. Julia begins to suspect Livia's part in all the sudden deaths in the family. Livia reveals Julia's orgies and lovers to Augustus, who in rage banishes her. Livia uses blackmail to have Lucius best friend arrange a accident and get Lucius killed. Tiberius is finally allowed to return to Rome.

Claudius studies a lot at the library and learns that both his father and grandfather was poisoned caused by their wish to reclaim the republic. By one of the historians at the library he gets good advice, to keep his studder and play the fool, advice that would keep him alive. Postumus reveals Livias plots to Claudius and encourages him to continue to play the fool. Claudius is now wiser than anyone suspects, and hides behind the face of a fool in order to keep alive. Postumus, Julia's son, has an affair with Livilla, daughter of Tiberius. Since Postumus is the last obstacle between Tiberius and the throne, Livia sets him up on a rape charge (Livilla) and he gets banished from Rome. Claudius gets married to a very tall bride and everybody gets a laugh.

Claudius, now a father, tells his brother, Germanicus, of what Postumus told him, about Livia's evil plots. Augustus visits Postumus on his desert island. When Augustus hear of Livias crimes he changes his will, favoring Postumus in order to prevent Tiberius to get the throne. Augustus realizes that Claudius is much smarter than people think and fins a new loyal friend in him. Livia tries to food poisoning her husband but fails. Augustus now only eats figs from the tree, not touched by human hands, but Livia poisons the figs. After his death Livia exchanges the will for one that favores Tiberius. (Many many years later Claudius finds Augustus original will.) Livia orders the murder of the remaining rivals and Tiberius finally rules Rome. Sejanus (Patrick Stewart) kills Postumus on his desert island.

Germanicus, Claudius brother is poisoned and dies. Piso is accused of murder (of Germanicus) and treason. Tiberius with help by the commander of the gard, Sejanus, tries to protect Piso. Piso reveals he has letters showing Tiberius involvment, threatening the emperor. Sejanus takes care of the letters but Piso has another letter involving Tiberius and Livia. Piso gets killed by his wife, before the letter could be read in the senate. Caligula is born. He is alreday a menace and is often found naked in bed with his sister Drusilla. Caligula is even involved in his fathers death. Caligula also sets fire to the house.

As Tiberius's chief advisor, Sejanus rules Rome with an iron hand, moving himself toward the throne. Meanwhile, an aged Livia asks to meet with Claudius.

Livilla's passion for Sejanus brings his Reign of Terror to a horrific climax.

Caligula takes over as Emperor. At first he is hailed as a savior. But eventually the monster is revealed.

Caligula's behavior becomes more and more erratic. Claudius works hard to control him but a conspiracy is growing among the soldiers. How can they rid themselves of their mad Emperor? And who will replace him?

Claudius has been appointed Emperor by the Praetorian Guard. He quickly proves himself capable of handling the role. But danger lurks in his own household.

Messalina's behaviour becomes ever more outrageous and it seems that Claudius is the only one who is unaware of this.