Caesar is dead. The assassins have run off. Three powerful men who supported Caesar join forces for the moment. They defeat the assassins. Then they fall to fighting one another. Soon it is down to two: Octavian and Marcus Antonius.
The empire has been divided between Octavian and Marcus Antonius. Marcus Antonius receives the eastern half. This is where all the wealth located. Octavian thinks that wealth should be his by right. He is Caesar's legal heir. Octavian is Caesar's nephew. Caesar adopted Octavian as his son so Octavian could inherit the family fortune.
Octavian goes to war with Marcus Antonius. Marcus Antonius has the beautiful Cleopatra VII of Egypt as his ally. Their forces are defeated by Octavian's forces at the Battle of Actium. Marcus Antonius and Cleopatra are burned toast. Back in Egypt, Marcus Antonius falls on his sword (commits suicide) rather than be taken alive by Octavian's men. Later, Cleopatra will die from a poison snake bite. The snake is smuggled into her room.
Octavian returns to Rome. He, and he alone, is now in command of the Roman Empire. The Senate is afraid of Octavian. How will Octavian use the fact the Senate fears him?