Romans have been attacking them from behind, though, for what's been going on a few days now. Meanwhile, Crassus gets a talking to from the good Senator. Rome is having a hard time with how long this campaign is taking: so Crassus beats him up and tells him to shut up. Which is sort of Crassus' whole thing.
In the rebel camp, Crixus and Spartacus still have general beef with each other, Agron is jealous of Nasir and Castus (who is really pouring it on thick, right?) and Laeta learns that Spartacus is a bit sweet on her. Meanwhile, Kore helps a lady give birth in a tent, and Spartacus figures out that she once belonged to Crassus. He lets her stay because hey, freeing slaves is what that guy is all about.
Meanwhile, Naevia and Crixus talk about what it'd be like to have a baby one day, and how much they love each other and how much they love killing Romans. Spartacus meets with his officers and reveals his big plan – to get his people over the Alps and let them run free. And this…actually makes a lot of sense. Crixus wants to attack Rome. They finally agree that the time has come to part ways. But first…they attack a town so that Spartacus can throw Crixus a party.
As the party is in full swing, Crixus and Spartacus catch up on all they've been through, including calling back to ol' stinky-pants Batiatus. Also, (called it!), Laeta and Spartacus make out in the storeroom and then have sex on a table. Meanwhile, Crassus tends to his wounds when Tiberius shows up and tells Crassus that Caesar was the one who convinced Kore to leave.
Crixus tries to convince Gannicus to leave with him but it's no use, so Crixus and Naevia decide to go and try to take Rome from the Romans, Agron and Nasir have a quick moment of smiling at each other, and Crixus and Spartacus have a very moving bro-dude sort of departure. And back in the Roman camp, Caesar and Tiberius have a fight that ends in rape. You guys, Tiberius is the worst. The. Worst. Also, four seasons of Spartacus and it's possible to not see something coming, y'know?
So then some time passes wherein Crixus, Naevia, and Agron kill a bunch of people in their path and Crixus gives a really impressive speech that calls back to the days of Oenomaus at the Batiatus ludus. Then they launch firebombs onto the Roman army. Meanwhile, Spartacus leads the rest of the rebel band over the hill and through the woods. But things aren't all going THAT great for Crixus, because just as he takes one army, another turns up: this time it's Crassus, Tiberius, and Caesar.
And this is where we say goodbye to Mighty Crixus, the Undefeated Gaul. He's beheaded, Agron is wounded terribly, and as for what becomes of Naevia, well – that's anyone's guess.