Some slave boys plot to assassinate Lotor, but fail miserably. They are kept alive, but only so they can be live bait for the Doomie's Voltron trap. The trap consisted of a shift in gravity that Haggar and Lotor could enact with the touch of a button, with the hopes that it'll incapacitate the Lions when they arrive.
It almost works, but unfortunately for the forces of evil, the Lions' power crystals easily recalibrate to compensate for the sudden gravity change and the kids are freed. However, Lotor isn't done with them yet, even as the slaves mount an intense revolt. Lotor launches a Robeast and Voltron forms to deal with the new threat. The Robeast has a really neat ball & chain weapon it whips at Voltron, giving the Defender of the Universe a real run for his money. Voltron even takes on some damage, as one of the wing type apparatus on Black Lion's back gets broken off. Voltron, of course, eventually triumphs. Once the Robeast is dispatched, Lotor and Haggar are forced to flee in disgrace.
Then the VF meet with the people of Zarkonia, whose planet is actually called Bravura...you know, "brave one"