Antony, Octavius, and Lepidus are gathered with a checklist of the men they plan to murder for conspiracy. Lepidus agrees that his brother can be killed as long as Antony agrees for his nephew to be killed.
Lepidus is sent to collect Caesar's will, to see if they can divert some of his money their way.
As soon as Lepidus has gone, Antony begins to talk trash about him. Antony thinks Lepidus is weak, so it's a shame that he'll be sharing power with Antony and Octavius in the triumvirate. Antony says he only took Lepidus's word about who should die because he's more experienced than Octavius.
The plan is to let Lepidus bear the burden of ruling while doing as he's told by the other two.
Octavius is more in the pro-Lepidus camp and insists that he's a good solider. Antony replies that his (Antony's) horse is a good soldier too – good at being led and ordered. To them, Lepidus should only be a puppet.
They then discuss the fact that Brutus and Cassius are raising an army, which they have to fight by allying their friends and funds.
They go off to sit in council and discuss how they'll fight their enemies and weed out the traitors.