A girl goes on an unexpected journey to save her little sister in this series opener. Pacey Packer daydreams of being the "brave and powerful" Lady Pacey, vanquishing foes and "bringing peace and justice to the world all by herself." Tasked with babysitting her younger sister, Mina, adventure-loving Pacey refuses to play tea party with Mina and her plush unicorn. But when she tries to relent, Pacey walks in on Mina being ferried out the window by a real live unicorn! Equally shockingly, Mina's unicorn toy is actually Slasher, a real unicorn who has been transfigured into the body of a plushie and can talk. Pacey follows them, but just as they arrive in the unicorn land of Rundalyn, Pacey and Slasher are separated from Mina. With snarky Slasher as her guide, Pacey uses her sense of adventure to brave carnivorous plants, oversized fauna, and other dangers to reach Mina. When Slasher and Pacey arrive at the Alpha unicorn's castle, a Mr. Tumnus--esque betrayal by Slasher reveals the cruel, haughty Alpha's plan to turn Pacey and her sister into stone statues. It's up to Pacey and her sister to save themselves, combining their styles of imaginative play. Two-color illustrations (a dull grape purple with black and white) lack the magic and energy that the story really needs, flattening the already two-dimensional style and lacking a clear intentionality. Pacey and Mina both have pale skin and straight, black hair. For settings where the Phoebe and Her Unicorn series has ravenous fans. (Graphic fantasy. 7-10) Copyright (c) Kirkus Reviews, used with permission.