Mostly Ghostly Series by R.L. Stine

A boy suddenly finds himself haunted by the friendly ghosts of two children while being pursued by an evil being.

Nicky and Tara still live in Max’s bedroom, and while they’ve found some clues, they still don’t know what happened to their parents. Meanwhile, Phears is still desperate to get his hands on Nicky and Tara, and to pressure Max into turning them over, Phears brings a Berserker Ghoul to inhabit Max’s body—and make Max go berserk when he least expects it! But Max, Nicky, and Tara aren’t giving in to Phears... moreNicky and Tara still live in Max’s bedroom, and while they’ve found some clues, they still don’t know what happened to their parents. Meanwhile, Phears is still desperate to get his hands on Nicky and Tara, and to pressure Max into turning them over, Phears brings a Berserker Ghoul to inhabit Max’s body—and make Max go berserk when he least expects it! But Max, Nicky, and Tara aren’t giving in to Phears. They have a few tricks up their sleeve—like one very talkative ghost cat, who’s taken residence inside the tunnel to the ghost world. . . . less

While Max is trying to help his ghost-friends Nicky and Tara find their parents, he accidentally angers an evil ghost named Mr. Morgo, who vows revenge.

This summer Max is going to Camp Snake Lake—where he will have to swim in a lake filled with poisonous snakes . . . where a Headless Ghost roams the fields . . . where he and his mostly ghostly friends Nicky and Tara will continue the dangerous search for Nicky and Tara’s parents. But first Max will have to face the evil spirit Phears again. Can Max learn the secret that will destroy this most terrifying ghoul for good?

Max’s parents are planning to sell their house and move the family far, far away. But Max can’t leave Nicky and Tara, the two ghosts who live with him. They need him. He’s the only one who can help them become kids again! Max has to stop his parents!

It’s October, and you know what that means . . . well, sure, Halloween, but it’s also Max’s birthday! Now that a bunch of ghosts have entered Max’s life, no birthday celebration will ever be the same! All Max wants for his birthday is a great party–but will he live to see another new year?

Max made a deal with Nicky and Tara, the two ghosts who live in his bedroom: If he helps them figure out how they turned into ghosts, they’ll help Max prove to his dad that he isn’t a worthless wimp. Well, Max is about to make good on his promise. There’s a witness who saw what happened to the kids. A witness who may know the secret to bringing them back to life. The problem is the witness is a chimpanzee! And Max is going to switch brains with him to learn the secret... moreMax made a deal with Nicky and Tara, the two ghosts who live in his bedroom: If he helps them figure out how they turned into ghosts, they’ll help Max prove to his dad that he isn’t a worthless wimp. Well, Max is about to make good on his promise. There’s a witness who saw what happened to the kids. A witness who may know the secret to bringing them back to life. The problem is the witness is a chimpanzee! And Max is going to switch brains with him to learn the secret. Will Max find the secret– or will he go from a worthless wimp to a worthless chimp? less

In a terrifying episode, Inkweed, the evil “Ghost of the Black Sleep,” has inhabited Max. The ghost has come to put Nicky and Tara to sleep forever!Inkweed is waiting, hoping for the moment when Max falls asleep— that’s when he can bring his crushing, evil powers to life. Nicky and Tara work frantically to keep Max awake. But they’re running out of ideas and after a few days of no sleep, Max is desperate... moreIn a terrifying episode, Inkweed, the evil “Ghost of the Black Sleep,” has inhabited Max. The ghost has come to put Nicky and Tara to sleep forever!Inkweed is waiting, hoping for the moment when Max falls asleep— that’s when he can bring his crushing, evil powers to life. Nicky and Tara work frantically to keep Max awake. But they’re running out of ideas and after a few days of no sleep, Max is desperate. He’s going crazy! But if he closes his eyes, it will mean the end of them all!Can Nicky and Tara keep Max awake long enough to banish Inkweed?Don’t close your eyes, Max! less