Bree West and Jack Bastian are now connected, to each other, and to the new black unicorn, Jonquil. With Jonquil's new powers, the unicorns have begun plans to crush the regime of the witches once and for all.
Then the witches attack, vaporizing a unicorn with their deadly new weapon. Powered by the alicorn sword, it is a bomb that can wipe out swaths of unicorns and humans alike. Now, conquering the witches is a dangerous and risky proposition.
But Bree has a plan. With the help of scavengers and thieves from her past, she and Jack will sneak into the high witch's fortress, dismantle the bomb, and take back the alicorn sword.