Barabas is rejoicing at the sound of the church bells, which are ringing to mourn the deaths of all the nuns.
Ithamore, high off of success, suggests they go massacre a nearby monastery. For symmetry, presumably. He asks if Barabas grieves for Abigail.
No, Barabas says, I'm just upset that she lived so long—he's clearly still angry that Abigail converted.
Jocomo and Bernadine approach. Before Barabas and Ithamore can slip away, the friars catch up and start yelling about damnation.
Barabas and Ithamore figure that Bernadine knows they poisoned the nunnery, and decide to play it cool.
Bernadine's in a tricky situation: he knows that Barabas set Lodowick and Mathias up, but he's bound by church law to not say anything. This results in a lot of half-finished accusations on his part.
Barabas, reckoning that he's toast for sure at this point, plays his final card: You know what? I've rethought this whole Jewish thing. It's not for me. In fact, I really want to be Christian, like you guys, and what's more I want to give all of my money away to whatever monastery I join.
Jacomo and Bernadine pedal backwards faster than Lance Armstrong does forwards, and instantly start fighting with each other over whose monastery will get Barabas and all his riches.
This is another one of those scenes where people are alternatively whispering and speaking aloud to each other.
Jacomo wins by persuading Barabas that his monastery is way more chill than Bernadine's (paired with the fact that Barabas is pretty sure Abigail told Bernadine everything) and arranges with Barabas to meet up that night.
Bernadine is still having a hissy fit over losing to Jacomo, but true to form Barabas then whispers to Bernadine that he's actually on his side, and not to worry.
Jacomo, promising to meet with Barabas later, leaves.
Barabas, alone, pledges to kill both friars: Bernadine because he knows too much about Barabas's crimes, and Jacomo because he was the one who converted Abigail.
Plus, killing is fun. Yay killing!
Ithamore comes back in, telling Barabas that Bernadine is asleep in a room where nobody can hear him if he cries out.
They strangle Bernadine with his own belt and then prop the body up so it looks alive.
Then they hide out and wait for Jacomo.
Jacomo returns to rendezvous with Barabas and, seeing Bernadine's body, thinks that Bernadine is trying to stop him.
He tells Bernadine to get out of his way, and when Bernadine of course does nothing (on account of how he's, you know, dead) he knocks the body down.
Ithamore and Barabas come out of hiding, all, "Goodness me! Look what you did!You've killed him!"
Jacomo thinks he's ok, though, because only Ithamore and Barabas have seen him.
Barabas is all, "No, no, justice must be served!"
Barabas declares that he'll remain a Jew; apparently these Christian friars are murderers.
Ithamore and Barabas tell Bernadine that they're going to take him to the court sessions the next day.