Gabby Duran raced through the woods, her breath scratching her throat. She could barely see. Only tiny slats of the late-afternoon sun squeezed through the thick canopy of leaves. Gabby raised her arms to shield her face from the branches snapping at her with every step, but she didn’t dare slow down.

If she did, he’d catch her.

He’d catch her if she kept running, too. He was a born hunter. He’d hear her sneakers pounding on the crinkled dry leaves. He’d hear her gasping for air. It was only a matter of time.

Gabby needed a place to hide. She needed it fast.

Finally, she saw it: a darker spot in the gloom. A cavelike opening at the bottom of a huge tree trunk. She veered toward it and dropped to her knees, then scooted back on the ground until she was curled up inside, her arms hugged around her bent legs.

She felt better, but she didn’t feel safe. She was still panting, her breath coming out in white-from-the-cold puffs that would surely give her away. She forced herself to breathe more slowly. In…out. In…out.

Better.

Gabby grinned. He’d never find her here.

But then she heard the sound. A ceaseless slither, a body sliding over dried leaves, moving closer…closer…

Gabby’s heart pounded. She ducked her head and hid her mop of curls under her arms, making herself as small as possible.

The slithering grew louder. Gabby squeezed her eyes shut. Maybe it wasn’t as close as it sounded. Maybe.

Suddenly the slithering stopped. Gabby didn’t dare breathe.

Maybe he didn’t see her. Maybe he’d move on.

Then a freezing dollop of goo landed on her hand. It chilled her to the bone, but before she could even react, the chill oozed up her arm, slicking between her shirt and the sleeve of her purple puffy jacket. It emerged as an icy blob against the skin of her neck, and…

“Aaaaa!” Gabby squealed out loud. “Okay, you found me!”

Gabby uncurled herself and tried to look at the glob, but it pressed so tightly against her neck it was impossible to see. As if realizing this, the creature extended a bulbous green pod out in front of Gabby’s face. The pod was shaped like a head, and it widened in the middle as if it was smiling…which it was.

“You’re too good at this, Glolc!” Gabby gushed. “No matter where I hide, you always find me.”

Glolc’s green, quivery head-shape shimmied with laughter. Then he hopped into the air, snapping his elastic-slime body away from Gabby and into a beach ball–sized sphere. Glolc hovered for a second, then Gabby caught him in her arms as he fell.

“What do you want to play now?” Gabby asked. But before Glolc could answer, Gabby’s cell phone rang from the back pocket of her jeans. Still sitting inside the tree trunk, Gabby struggled to reach it, rocking to her right and trying to balance Glolc in one arm, but Glolc quickly solved the problem. He extended an amoebalike blob from his body, wrapped it around the phone, then snapped it back into place. Glolc disgorged a smaller tentacle to press TALK, then extended the phone to Gabby’s ear.

“Hello?” Gabby said.

“Hi!” chirped an upbeat and very human female voice. “It’s Esleil—I’m home!”

“Oh, great!” Gabby replied. “We’re playing outside. I’ll have Glolc back in no time.”

Glolc clicked off Gabby’s phone, dropped it, then melted into a giant splotch of green ooze that glopped heavily over Gabby’s arms.

“I don’t want to go, either!” Gabby laughed. “But it’s time. Your mom’s back. And I promised my mom I’d be home for dinner.”

Reluctantly, Glolc congealed his body back into an amorphous mound and rolled out of the tree hole. Gabby scooted out after him, adjusted the ever-present purple knapsack on her back, and moved with him through the woods. Looking down at the little blob, Gabby tried not to giggle. Glolc only came up to Gabby’s knees, and he resembled nothing so much as a beanbag made of lime Jell-O, but the way he slumped over as he slithered along on his protruding pseudopods made him look just like a human kid disappointed his playtime was about to end.

Gabby was so entranced by the way Glolc moved that she forgot to look where she was going. Her foot came down on something firm but strangely squishy.

She looked down and saw the lifeless body of a young boy staring up at her. Her foot had landed on his arm.

“Oh my gosh!” she gasped. “I can’t believe we almost left this here! You have to get in.”

A lump of Glolc’s body turned toward Gabby. It looked at her pleadingly.

“I know, but your mom said you could only have it off in the woods.” Gabby thought a second, then smiled. “Tell you what—once you’re in, I’ll break out the string and we can play cat’s cradle.”

Glolc’s gooey form undulated as he thought it over, then he slithered closer to the unmoving body. He extended a sausage-thick section of himself toward the boy’s nose, then the nostril flared wide as Glolc’s gloopy green mass slid inside, an explosive sneeze in reverse.

A second later, the boy’s brown eyes focused. He wrinkled and rubbed his nose while he sat up. “It’s so uncomfortable in here,” he complained. “Everything pinches. How do you stay cooped up like this all the time?”

“I manage,” Gabby said.

She shrugged off her knapsack and rummaged inside until she found her favorite cat’s cradle string. Gabby had showed Glolc the game when they first met and he’d loved it right away, but his gloppy pseudopods couldn’t handle the intricate finger motions. He could only play when he was inside his human suit.

As Gabby and Glolc tromped through the woods, trading the string back and forth between them, Gabby marveled over how normal it all was to her. Only two months ago, she nearly went into shock after she saw an eight-year-old boy transform into a gigantic slug-monster. Now she was playing cat’s cradle with someone who had just been an oozing sludgeball, and it was as normal as having a stuffed-animal tea party while soaring over the Atlantic Ocean in Air Force One.

Okay, the tea party thing sounded unusual, but to Gabby it wasn’t. The president of the United States was one of her best babysitting clients, and her other regulars included rock idols, movie stars, sports heroes, and of course all the neighborhood kids she could fit into her schedule. Some people called Gabby a “super-sitter,” but Gabby didn’t agree. She just loved kids. All kids. She didn’t buy it when people said some were “difficult” or “impossible.” Gabby thought anyone who said that kind of thing hadn’t worked hard enough to figure out what the kid was really all about.

That’s why Gabby was recruited by A.L.I.E.N., the Association Linking Intergalactics and Earthlings as Neighbors. As Gabby understood it, A.L.I.E.N. was like an embassy for aliens living on Earth. The group knew that humanity would rise up in a giant panic if they knew about the aliens, so A.L.I.E.N. helped by creating things like Glolc’s human suit. They also helped by finding Gabby, a babysitter who would keep their secret and wouldn’t panic if a Flarknartian morphed into a piano, or a Pimsplilite burst into flames, or a Yabukerant cast off its human form and became an amoebic beanbag blob.

Gabby and Glolc emerged from the woods into Glolc’s grassy backyard, where Esleil waved down to them from the porch. An ancient, pea-green Toyota Corolla with peeling paint spluttered in the driveway next to the house. Its license plate read 4118-251, the first seven numbers of Gabby’s official A.L.I.E.N. Associate number. This was Gabby’s ride home, and her heart raced a little at the sight. Normally, Gabby hated to leave the kids she babysat, but today she couldn’t wait to get home. Her mom had promised she had “something big” to share with Gabby and her little sister, Carmen, at dinner.

True, Gabby’s mom, Alice, was a caterer, so at dinnertime “something big” was usually an oddball delicacy like deep-fried onion rings served as a puffy foam, or fish roe consommé. But there was something about the way Alice said it, a gleam in her eye that told the girls this wasn’t just about the food. It was something bigger. Something better.

Gabby said quick good-byes to Esleil and Glolc, ran to the Corolla, swung off her knapsack and tossed it inside, then slid in herself, yanking hard to slam the squeaky door behind her.

“Let’s go home!” she cried happily, though of course no one answered. A thick, orange, nubby carpet separated the back of the car from the front.

Gabby sighed. She didn’t need the luxury of the limos Edwina, Gabby’s main contact at A.L.I.E.N., usually drove, but she did miss the company. Edwina was an older woman who always wore her hair in a severe bun, sat tall and cold, and spoke to Gabby mainly in riddles, clucks, and exasperated exhortations that Gabby stop asking so many questions. Still, Gabby liked talking to her.

Unfortunately, Edwina was “on assignment” somewhere in the outer reaches of the universe. Gabby didn’t know much about the larger workings of A.L.I.E.N., but she got the sense that the organization wasn’t exactly perfect. Edwina hadn’t been happy about leaving for her current mission, and she told Gabby before she left that she certainly wasn’t going to trust anyone else with the hands-on business of running the Unsittables program in her absence. For the last week, Gabby had received all her A.L.I.E.N. assignments via code. Her rides arrived in random, ramshackle vehicles, always marked with her Associate number, always with the driver walled off so he or she couldn’t communicate with Gabby in any way.

Gabby’s foot bobbed up and down excitedly as she thought about her mom’s big surprise. Gabby and Carmen both started winter vacation in a week, and their mom had been hinting that it would be great to “take a break.” Could she be planning a family trip? They hadn’t had one in…well, ever, really. When Carmen was little it was too hard, and since their mom’s catering company took off, Alice always ended up working over school holidays. Sure, Gabby herself went all over the world to babysit—just last week she’d traveled to Washington, DC, to play French horn with the Brensville Middle School Orchestra at MusicFest, but a trip with Alice and Carmen?

It would be unbelievable, no matter where they went. Especially if…

Gabby’s hand floated toward her chest. She felt her dad’s army dog tags hanging under her shirt. The tags had mysteriously appeared in her pocket after one of her babysitting assignments. Gabby still had no idea how it had happened, but that was okay. She was just grateful to have them. She wore them around her neck every day.

Gabby squeezed the dog tags tightly. As the edges dug into her palm, she wondered…could her mom’s surprise be a trip to Costa Rica to see Dad’s family? The aunts and uncles and cousins Gabby and Carmen had never met? Could Mom be planning a reunion with the family Dad had lost touch with years before he went off to war and disappeared?

Gabby smiled, picturing it: her little family of three swarmed by boisterous relatives telling wild stories about her dad’s life. They’d take Gabby to her dad’s favorite spots, feed her his favorite foods, pull out old photo albums…

“Oof!”

The seat belt dug into Gabby’s stomach as the car jolted to a hard stop. But Gabby only smiled. She threw the car door open and raced up her front walk.

One more minute and she’d know her mom’s surprise.

She couldn’t wait.