On the day of the wedding*, Albert sneaks in disguised as a servant and breaks Eugenie out. Cavalcanti is arrested for impersonating an aristocrat, among other crimes.
* it's technically a pre-wedding financial commitment ceremony that Danglars is using to reassure investors.
The Count confronts a fleeing Danglars and ruins him.
At Villefort's trial, Cavalcanti testifies that he's his son, then poisons him with a needle.