Weekend at Poison Lake is the eighth of the special editions of Give Yourself Goosebumps. It was preceded by Trick or...Trapped! On the front cover was a swamp lake with spiders, dragonflies, and a poison dart frog around the grass at its bank. A blue swamp creature with webbed hands was emerging from the murky waters.
This book has four almost fully distinct main storylines. Rather than providing the reader with a choice in order to determine which storyline is followed, this book requires the reader to pick a lucky number. The lucky number is then employed at several points throughout the book, making the course of the story more random than voluntary. Which storyline you follow depends on the lucky number you choose (and thus, the page you first go to):
Your friend Nathan's parents are staying at Poison Lake, so Nathan invites you and your other friend Tamika to come along.The first thing you do is swim in the lake, but a neighbor warns you that swimming is not allowed because the lake really is poison. But being in the water makes you smell disgusting, and you can't shower off the stench. This storyline is based around you trying to get rid of the smell while surviving a bunch of creatures (insects, wolves, etc.) that are suddenly drawn to you because of it.
You go on a family vacation to Poison Lake. Your parents have heard the lake is dangerous, so they ban you from the water. But your bratty little brother dares you to swim in the lake, and you do it. Your skin turns green and luminous, and then a spaceship appears in the sky above you. You have been poisoned by the water and need to get an antidote from the aliens, but they will give it to you only if you can get an ice cream company's secret recipe.
You're staying at Poison Lake with your family, who have been warned that the lake is poisonous. An old lady tells you that this isn't true. Jewels were hidden in the water after a robbery, and a couple who had witnessed the robbery (the Bittermans) made up the story about the lake being poison, so they could get the jewels for themselves. You decide to search the lake for jewels, but you're in danger from both the Bittermans and the horrors that await you in the lake.
While walking your dog Harley at Poison Lake, an old man encourages you to swim in the water. You decline because everyone knows the lake really is poison. The man then turns into a moss-covered monster and tries to force you into the lake. You and Harley must now escape from the "Moss Man" who wants you to swim in the water.
- Your terrible smell causes a wolf that was chasing you to fall unconscious, but the stench knocks you out cold as well. It's possible you get eaten when the wolf comes to.
- You're devoured by a mass of rats that were attracted to your smell.
- Eaten by Bigfoot while reaching for your lucky number (apparently, you took too long to calculate the page number from the book's instructions.)
- Bigfoot takes you back to his cave. You try to escape, but then you see that you're growing fur all over. You realize that the water turned you into a lake creature, and Bigfoot wanted you because you're now one of his kind. You stay with Bigfoot and have to live in the forest forever.
- You find the recipe but the writing is smudged, so you're not sure if it says to use 3 quarts of cream or 8 quarts. You decide it must be 8, but when the aliens eat the ice cream, they have heart attacks and die from all the cholesterol (this is a ridiculous ending.) The spaceship takes you back to earth, but you still don't have the cure you needed, so you will die from your illness in a matter of hours.
- You get the recipe for the ice cream, but the aliens tell you it's no good; the key ingredient is cola, and they don't know how to make it. The recipe for cola is so highly guarded you will never be able to get it for them, and now you're going to die in agony from the poison.
- The aliens fire a disgusting substance into your mouth from a blaster weapon. You decide not to use your lucky number at this point. The book ends the story there, and tells you that without the lucky number you have no chance of surviving this storyline.
- When you use your lucky number 3, you get bad luck. You feel three times sicker, and three spaceships appear instead of one. The book tells you to try again for a better ending.
- You decide that going into Poison Lake is too dangerous. The book scolds you for your wimpiness and ends the story there, as you aren't brave enough to have any adventures.
- You tell your parents all about the Bittermans' plot. Your father is so concerned that he takes you straight home, so you never get the jewels. The book says it's your own fault you got such a boring ending; you shouldn't have got your parents involved.
- You row out into the lake and find the jewels, but the Bittermans catch up to you. They tie you to a heavy anchor and throw you overboard. You drown and they get the jewels.
- You spot diamonds in the water and swim towards them. But they turn out to be encrusted in the forehead of a lake monster, which ends up swallowing you whole.
- You decide not to use your lucky number after the Moss Man kidnaps your dog. The book scolds you and ends the story there.
- In an effort to get rid of the smell from the lake, you take a bath in a mixture of ingredients like lemon, ketchup, vinegar, etc. that are supposed to remove bad smells. This works, and the resulting combination both smells and tastes great. You become a millionaire from selling the mixture as "Bigfoot Sauce."
- Nothing you do gets rid of the smell, so Nathan's parents take you home. You eat a piece of chocolate cake while waiting for your parents to get back. You tell your mother the whole story, but she says you don't stink any more. It turns out that chocolate cake keeps the smell away, so now you have to eat it every day for the rest of your life (you are very happy with that.)
- You call the FBI to help you. As soon as you get off the phone, the aliens land and administer you with the cure. When the FBI arrive, you have no proof any more and they don't believe your story. You become rich and famous from appearing on TV to talk about your "delusion" of aliens.
- An alien creature comes out of your mouth and devours JoJo. You lose consciousness. When you wake up, Ben tells you he gave the aliens the recipe. You spit out JoJo and realize that you have been cured. Everything seems fine until you point out the cabin you're staying in - Ben warns you that it is called Vampire Cabin, and no one is safe there.
- The Bittermans are arrested and you find the jewels, which belong to the old lady. She hadn't told you that they were hers, but she had faith that you would be able to get them back for her. You have saved the day and proved that the lake isn't poison, so now everyone can enjoy the water. The Mayor and townspeople are so grateful that they rename the lake after you, and the old lady offers you a reward out of the jewels.
- Jake refuses to help you search for the jewels because his dad won't let him swim in the lake. He tells you that finding jewels in the lake would be impossible anyway. You decide he's right, and instead have a fun vacation hanging out with Jake and swimming in his family's pool. The book points out that you are lucky to be alive, and it wasn't wise for you to get mixed up with jewel thieves.
- The Moss Man takes you to the bottom of Poison Lake, whereupon you find out you were born there and belong to a tribe of lake people. You were given to humans to raise, but now it's time for you to come home to your real family. You feel at great peace and are happy to finally be where you really belong.
- The Moss Man turns out to be just a guy who wanted you to swim in the lake to prove it isn't poison. The townspeople are so grateful that they rename the lake after you. Your parents reveal that they have bought five houses around the lake to turn into a vacation resort, and now you'll be rich because of the lake's newfound fame.
- The Moss Man turns out to be your cousin, whom your parents hired to dress up and scare you because you love horror stories. You all have a laugh about it and go for a midnight swim in the lake.
- Using your lucky number takes you back in time to the afternoon. The police arrest the Moss Man, who's just a guy in a costume, and had made a bet that he could get you to swim in the lake. You are warned that the lake really is poisonous, but the police refuse to tell you what will happen if you swim in it; you'll have to get a different ending if you want to find out.
- There are thirteen bad endings and ten good endings, however the cover claims that there are more than 20.
- This book has a near-equal ratio of bad to good endings, and may therefore be considered the easiest Give Yourself Goosebumps book.
- Storylines 2, 3 and 4 have exactly four bad endings and two good endings.
- Storyline 5 is the easiest: you can only get a "bad" ending (the book refusing to go on any further) if you decline to use your lucky number. All the other endings are good, and the Moss Man isn't a danger to you in any of them.
- "Ben and JoJo's" is an obvious parody of Ben & Jerry's ice cream.
- Two endings have the lake being renamed after you.
- This book is now considered unpopular among fans of the series, due to the absurdity of some endings and the "lucky number" gimmick relying on random chance rather than good decision-making.