Cindy has a massive fear of the closet, so it doesn't fill her with confidence when she checks one night and sees a glowing green light coming from within. She talks it out with her friends, and they basically take a wait and see approach. Adam does, however, tell her to call him if she gets scared later that same night. Naturally, the light comes back and starts taking over her room. Cindy manages to make one phone call before a giant green monster pops out and drags her away.
Adam gets there and finds her missing, so he calls the gang and they all meet in her bedroom. Watch decides that since she had such a big fear of the closet that she made the monster inside come to life. Sally remembers that this kid George has a massive fear too. In a completely dick move, they go over to his house, and Sally keeps riding him until he's terrified. The monster then comes out of his closet, they grab it, and Adam, Sally, and Watch get pulled through the closet.
Cindy wakes up in a completely new world with an elf guy watching her. He introduces himself as Zeta and makes it clear that he really dislikes humans. His uncle is basically the ruler of the world (High Lord). Though he doubts his uncle will help her, he lets her go with him, but he does point out that he won't help her at all. It turns out that the monster is actually a Shadow and that the Shadows live in his world.
The others arrive, find her footprints, note that she has someone with her, and decide to follow her. Trust me, it's not that interesting.
Back to Cindy. The Shadows keep attacking, and Zeta keeps helping her, despite what he said earlier. She flirts with him, though she was all over Adam earlier in the book. The Shadows get closer, grab her, and take her back to their camp. Zeta then hooks up with her friends, admits that he likes Cindy (shocker), and takes them to the camp. They use Watch's flashlight to scare the Shadows and get Cindy back.
Zeta keeps talking about his uncle and some friend of his uncle. Turns out that both of them now side with the Shadow. There was something about how working with them will keep them from attacking their people, even though they still attack the people living there. I don't know, whatevs.
Zeta's girlfriend then shows up, which tots annoys Cindy because she thought he liked her. She gets there not long after Zeta's uncle basically arrests them and puts them in jail. They find out that the only thing separating them from home is a literal curtain between the worlds. Girlfriend uses her uncle's resources to get them horses, and they all ride to the tallest mountain.
High Lord then pops up and demands that they all follow him. He's kind of an asshat, but Watch comes up with an idea. He says that if they laugh at the Shadows, it will make them disappear. Something like how they feed on fear and laughter is the opposite of fear. Sounds like some Yoda crap to me. They laugh, the Shadows disappear, and High Lord is suddenly a nice guy again. He even offers them jobs as his guards.
After turning him down, they go higher up the mountain and call out to their friends. They stick their arms through the curtains and literally pull their friends out. Luckily it's a Sunday and still early in the day, so their disappearances weren't noted by their parents.
*I kind of love Sally. She points out that she's surprised she gets along with Tira given that she usually hates pretty girls.
*Sally also points out that they should probably focus more on getting home and less on solving the problems of another world.
*The curtain thing is as ridiculous as it sounds. It is literally just a plastic curtain separating the two worlds. Their friends poke their hands through and pull them out.
*Cindy comes across a little Jessica Wakefield-ish. In the end, she decides that it's okay if Zeta has a girlfriend since she likes someone else. She even tells him that they make a cute couple.
*Poor George! They literally scare the crap out of him and then just leave him alone for the night. When it ends, they kind of tell him what happened and then just take off without making sure he's okay.