Jag läste den här boken för 10 år sedan jag tror. Det publicerades förmodligen på 90-talet, men möjligen 80-talet. Huvudplotten som jag kommer ihåg involverade en gymnasieflicka som faller för den nya studenten. Han avslöjar att han vet hur man ska "röra sig i en annan riktning" och besöka högre orderdimensioner där man bara kan se vissa sidor av föremål och varelser. Det finns monster slags varelser som de gömmer sig från. Jag tror att flickan oavsiktligt reser sig till femte dimensionen och han måste rädda henne. Jag tycker att det var svårt, kanske apelsinhölje.
Låter som pojken som återvände sig själv, av William Sleator.
Från Wikipedia:
A high school girl named Laura grows suspicious when a report of hers appears in mirror writing, and Omar, the weird boy next door, makes it go back to normal. Furthermore, he seems to be parting his hair on a different side than usual. He first refuses to explain what's going on, but after she repeatedly coaxes him, he reveals that he has access to the fourth dimension, where he accidentally "reversed" himself. He eventually allows her to visit it under his supervision, but he warns her that it is extremely dangerous and that he is violating some agreement by letting her in on the secret. She tries to use her access to the higher dimension to impress Pete, a popular boy she wants to go to the school dance with, but after she seems to disappear into thin air and unlock a door from the other side, Pete realizes something funny is going on, and she feels pressured to show him the truth, without Omar's knowledge. When she brings Pete into four-space, they lose their way and end up as the captives of four-dimensional creatures. Unfortunately, she determines that escaping might threaten the very existence of her own world by making the powerful 4-D creatures aware of it. With Omar's help, she finds a safe way out and learns the truth about how he came to know about other dimensions.
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