Set in an alternate America where witches ended their persecution over 300 years ago by cutting a deal with the burgeoning government to fight for their country, the series follows three young women from basic training in combat magic into early deployment. In this world, the traditional roles of gender and power are flipped, with the more dominant women on the front lines fighting looming terrorist threats that are familiar to our world, but with supernatural tactics and weapons.
The unit travels to Salem Town for an annual witch celebration, but an unexpected disturbance throws the proceedings into chaos. Tally wonders if she made the right choice to embark on a military career when witch-hate and her own mother stand in her way. Smarting from Alder's denial of her request to switch units, Abigail attempts to bury the hatchet with Raelle. Raelle grows closer to Scylla, while the unit impresses Anacostia in Windstrike training.
Fort Salem excitedly greets male visitors on the eve of Beltane, but Raelle and Scylla's budding romance is interrupted by the arrival of a mysterious man from Scylla's past. One of the male witches catches Tally's eye, but she is unsure of how to proceed. Meanwhile, Alder attempts to convince the Hague, an international military council of witches, to follow her strategy against the Spree and is startled by the news of an escalating humanitarian crisis in the Tarim Basin.
The base reels from a traumatic event, while Raelle tries to come to terms with her role in the tragedy. Scylla attempts to evade Raelle's increasingly pointed questions. Abigail works to impress her formidable rival, Libba. And Tally's connection with Gerit grows during Beltane, a sacred holiday honoring fertility traditions.
The unit travels off base for the high society wedding of Abigail's cousin. Raelle throws herself into her relationship with Scylla, who, unbeknownst to Raelle, faces an impossible choice. Abigail becomes disillusioned with her privilege while amongst the notable Bellweather line. And Tally gets hit with two life-altering revelations that change the very fabric of the unit.
Abigail has to come to terms with her vulnerability in the aftermath of a horrific event. Tally struggles with being supportive while also keeping a secret from her unit. Raelle takes extreme measures to connect with Scylla.
Abigail forges a connection with Adil, a new visitor to base camp, and pushes a devastated Raelle to help him save a life. Tally uses Gerit as a distraction from her increasingly burdensome secrets. Anacostia probes into Scylla's past.
The witches' training culminates at Citydrop, their final training exercise; devastating secrets come to light, splintering the unit and forcing Tally to question her blind trust; a Spree threat changes the course of the cadets' lives.
In the aftermath of Citydrop, the unit comes closer together, while their distrust of Alder grows; Abigail is faced with eulogizing a fallen soldier, while Tally learns something new about Gerit; Anacostia grants one last favor to Scylla.
Raelle, Abigail, and Tally graduate from Basic Training making Abigail more desperate than ever to prove her unit belongs in War College. Alder eyes the unit for a rescue mission while Anacostia and Scylla find common ground.