Sweet Valkyrie High
Now that Lauren has used the serum to make herself Fae, making out is definitely a new experience for Bo. It's not a bad thing; it's just new and different than it was. Tamsin interrupts these hazy blue shenanigans because a letter has arrived. A letter that turns out to be payment from Hades for delivering Bo. This infuriates Tamsin and she decides to exact her revenge. After Trick tells her that it's possible Freya tricked Hades into taking the underworld all those years ago, she develops a plan: to head back to Valhalla and get Freya to trick Hades again, thereby taking his soul back to Tartarus. Tamsin and Stacy head off to find a portal to the underworld, and enlist the help of Acacia who isn't so keen to help them.
Stacy and Tamsin remember where there's definitely a portal: their alma mater, Valkyrie Academy. In flashbacks, it's clear that Acacia was, so many years ago, their teacher. And she did not play by the rules. Where most Valkyries believed their mission was to help take soldiers to the next world, Acacia believes that a Valkyrie fights.
Meanwhile, back in the present, The Morrigan desperately wants to be Fae again, but she won't let Lauren run any tests. When Lauren DOES run them, she finds some pretty tough news: The Morrigan is very sick, and turning her back to Fae could kill her. Also? Everyone's pretty mad at Lauren because instead of turning The Morrigan, she tested the serum on herself.
When Tamsin and Stacy realize they're having a hard time finding the school's portal because they need a teacher to help them, Acacia turns up with news from the other side. Freya is dead and the girls are going to have to find another way to get Hades to Tartarus. A flashback illustrates that Acacia was the one who got Tamsin to be a less of a goody-two-shoes and more of a fighter. The first lesson she gave Tamsin? Doubt. It's a tool used to take away the power of another Valkyrie, simply to doubt them. Tamsin can't seem to do it for Acacia. This caused a lot of problems back in the day. Acacia's attempts to train Tamsin got Acacia fired and Tamsin expelled. So, now, when Tamsin discovers that Freya isn't actually dead, Tamsin is able to doubt Acacia for the first time.
In order to save The Morrigan, Lauren goes to Hades to ask that he use his handprint, the kind he uses to save Fae. The problem is Hades can only meld with the flesh of Fae, so instead he tells her to keep fighting.
Back at the Academy, Tamsin casts doubt toward Freya about her trickery of Hades. Freya is pretty powerful, and thus she can withstand Tamsin's power. But when Acacia and Stacy join, in, she's no match. Freya confesses that what Hades wants is to build an army and so he used her to try and help him. The three defeat Freya and send her home, but not before Tamsin deposes Freya and makes Acacia ruler of Tartarus. Acacia has one last bit of teacherly advice: being a Valkyrie means you can't tap into your emotions until you've felt them. Apparently, since Tamsin learned to be vulnerable with Bo, now she can exploit vulnerability.
Hades/Jack, meanwhile, decides that he's finally going to get out of that box he's been living in, and go for a bit of a walk in the world, while Bo and Lauren make up in their conversation about what's going on with them. The Morrigan interrupts them and the three drink to her health. Finally, Tamsin tells Bo what she knows: Hades is trying to start an army. Bo worries that he's playing them, and Tamsin says it's time they got to the bottom of things.