At the end of act 1, what plan has Cassius devised?

Answer: Cassius has devised a plan to persuade Brutus to act against Caesar.

Explanation:

Brutus is a character from Shakespeare's Julius Caesar. He is Caesar's friend who joins a conspiracy against Caesar.

At the end of Act I, Scene II, Cassius plans to convince Brutus to join a group of conspirators. Brutus is essential for the murder plan, because Caesar trusts him, as opposed to Cassius.

Cassius thus devises a plan to write letters and throw them at Brutus's window. The letters are intended to discredit Caesar. Cassius wants Brutus to believe that those letters come from Roman citizens, which will make him change his opinion about Caesar and participate in the murder plot.