Zoe must figure out how to keep a giant kitten safe in this magical adventure about change, expectation, and accepting all for who they truly are—regardless of shape or size. Zoe named the kitten Pipsqueak, because she was so tiny, and promised to always take care of her. Then the kitten grew. And grew . Now she’s bigger than a horse—and talking as well! Fleeing into the woods to escape the curious eyes of the Internet, Zoe and her best friend, Harrison, must keep the giant cat hidden as they desperately search for a way to return her to normal size. If they don’t succeed, Pipsqueak may never be safe again. But why did she grow so large in the first place? And what if trying to change her back leads to even greater danger? "Durst masterfully interjects humor into a suspense-filled plot that twists and thickens as the group reaches its destination. A surprising but satisfying resolution brings this charming fantasy to a close." - Booklist (starred review) "A fast-paced, engaging fantasy novel that cat lovers will adore." - School Library Journal "Magical animals become a kooky, sweet metaphor for growing up." - Kirkus Reviews "Durst imbues her tale with humor, thoroughly embracing its unusual premise with a sense of wonder." - Publishers Weekly "Come for the horse-sized kitten, but stay for mystery, friendship, adventure and even more exceptional animals— Catalyst is a joyful read that's full of surprises!" - Emily Jenkins, New York Times bestselling co-author of the Upside-Down Magic series Sarah Beth Durst is the author of the New York Times bestseller The Spellshop , as well as over twenty-five fantasy books for adults, teens, and kids, including the Queens of Renthia series,  Drink Slay Love , and  Spark . She has won an American Library Association Alex Award and a Mythopoeic Fantasy Award and has been a finalist for the Andre Norton Nebula Award three times. She lives in Stony Brook, New York, with her husband, her children, and her ill-mannered cat. Chapter 1 'NO KITTEN IS THAT SMALL," the text from Harrison read.       Zoe texted back, 'smaller than my hand.' She crouched next to the tiny ball of fluff. Shivering, it had wedged itself between the trash can and the garage door. Zoe had spotted it when she'd dumped a bag of crumpled wrapping paper and used party plates into the can.       She cooed at the kitten, 'It's okay. Don't be scared. You'll be all right.' Checking around the garage, she searched for a mother cat or any other kittens, but didn't see anything. She heard the chirp of crickets, cars on a distant highway, and the hum of her family's voices through the open window of the brightly lit kitchen. But no meows.       Her phone binged with a one-word text: 'Photoshop."       'If Photoshop," Zoe typed, 'kitten would be riding a velociraptor."        Bing. 'sweet.' Then: 'still Photoshop."       'Come see."       'Busy."       She sent him an eye-roll emoji. He wasn't busy. She knew for a fact that he was camping in his backyard, next to her own, and that he was most likely 'busy' separating the raisins from the M&M's in a bag of trail mix. Laying her hand flat, palm up, she waited as the kitten stuck out its little pink nose and sniffed her fingers. Zoe whispered, 'Let me help you."       The kitten crept forward into the light from the garage, and Zoe decided to think of it as a she, because the fuzz above her eyes looked like a cartoon cat's eyelashes. She was trembling, which made her orange, black, and tan fur quiver all over. Her ears were flattened, and her tail was tucked between her hind legs. She looked so miserable and so hopeful at the same time that Zoe felt her heart melt. Poor little thing, she thought. "I can't keep you," Zoe warned. 'my parents said no more animals in the house, not after the mix-up with the skunk."       'mew?' the kitten said.       'Long story," Zoe said. 'tonight you'll be my secret, and tomorrow I'll help you find someone who can take care of you."       She stayed still while the kitten sniffed her hand some more. Her nose and whiskers tickled, but Zoe didn't laugh. Gingerly, the kitten placed one paw on Zoe's palm. "You can trust me," Zoe whispered. "Everything's going to be okay. Promise."       Cupping her other hand behind the kitten, Zoe scooted her fully onto her palm. She really is smaller than my hand, Zoe thought. She stood, cradling the kitten close. The kitten tensed and then relaxed as Zoe carried her inside.       Zoe heard the clink of glasses being loaded into the dishwasher in the kitchen as her parents and brother cleaned up from her birthday party. Her cousins, aunts, and uncles had all swarmed to their house for the usual hamburger, hot dog, and cake celebration and had left after Zoe opened her presents. Zoe was supposed to be in the kitchen, helping to clean. She tiptoed past and up the stairs to her bedroom.       Tucking the kitten against her with one hand, she used her other hand to drag