The Romans have come! The Romans have come! Into the sleeping Spartacus' hideout! Naevia sounds the alarm! Everyone scurries into position! And then…oh, it's just Spartacus. He tells them that if they had been real Romans, this would have gone badly. It's basically a drill.
Back at the villa, Glaber tells Seppia he loves her, and she's having some second thoughts because she knows he killed her brother. And then the doors fly open and in comes Illithiya, looking insane, and in desperate need of one of her signature baths.
Spartacus' army starts to question his judgment and he tells them that he's better than the Romans. The team is having a hard time working together, and the Romans will be around soon. Meanwhile, Mira and Spartacus have a conversation about how Lucius has died and how they probably won't be in love anymore because she tried to kill Illithiya and also Spartacus still loves his dead wife.
Lucretia and Illithiya have really grown. They've had moments where they're terrible to each other, and Illithiya calls out Lucretia on that. But now they forgive each other. And then it's right back to scheming: Lucretia and Illithiya are right back to plotting against Glaber, via Seppia.
Ashur and Glaber plot to find the temple where Team Spartacus is hiding. A big battle is forming, team. Back at the hideout, everyone gets a little bit drunk because Spartacus has a plan to bond them all as a team. Back at the ludus, horrible Ashur (who is now speaking of himself in the 3rd person because he's horrible!) tells Lucretia that he'll be getting his freedom after they kill Spartacus, but also he'll be getting her and the ludus.
A hitch in Glaber's plan to attack Camp Spartacus: Varinius has arrived from Rome. And he wants Glaber to go back to Rome and abandon his pursuit of Spartacus, because it's time for Varinius to take over. It turns out that Seppia has called Varinius and all of this is her doing.
Back at the Spartacus party palace, everyone is kicking the feathers out of each other for fun. (It was a different time, and this was a thing.) Spartacus calls Crixus and Agron to fight against Gannicus and Oenomaus. Spartacus has really thought up some good schemes for the bonding party. While the dudes fight, Naevia and Mira talk about their boyfriends.
Back in the villa, Lucretia tells Seppia that the obvious answer to her problems is murdering Glaber. And Seppia isn't necessarily against the idea; she's just kind of weak sometimes. Then some really messed up stuff starts happening: Seppia gets Glaber naked, hits him with a jug of wine, then Illithiya shows up, stabs Seppia with a knife, cuts her throat, and kills her dead. Then Illithiya tells Glaber that since they're both monsters, they should join up together. And then she demands they have sex. And they do.
Gannicus and Spartacus hang out on top of the wall when they see the signal. Spartacus takes his army out into the woods to meet up with the invading Romans and a big fight takes place there. Meanwhile, the whole thing is a ruse to make it look like the rebels are in retreat! But they're not; they're just luring them back to the base.
Just then, a ball of fire comes flying into the hideout. Oh no, the battle is going on! And Varinius is hit directly by one of the firebombs. The hideout is under attack and it's not going great for Team Spartacus. They have to retreat! But now there are invading Romans! The plan has failed! The wall has fallen! Team Spartacus heads off into the mountains. And Glaber decides to leave them up there until they're hungry and insane and come down.
And then, echoing the battle cry from all the other seasons, Glaber proudly claims he's going to "kill them all."