What major decision do the conspirators take concerning Caecar in Scene 1?

Cassius, Casca, Decius, Cinna, Metellus and Trebonius, all of them conspirators against Caesar, have arrived at Brutus' home. Brutus invites them in and Cassius takes him aside. Soon Brutus rejoins the group of men and shakes all their hands, agreeing to join them in their murderous quest to kill Caesar.