Ollie’s Pack follows Ollie and his backpack, which doubles as a powerful portal allowing an array of monsters to travel from the Monsterverse into Ollie’s world on Earth. Throughout the series, Ollie and his two best friends must protect the earth from the horrifying monsters that have escaped, while often utilizing the helpful monsters who assist with their everyday tween problems, like sneaking into a movie or winning their school’s Battle of the Bands contest. No matter the circumstances, Ollie’s thirst for adventure undoubtedly gets him into trouble that only he and his friends can resolve.
After recess gets canceled, Ollie directs Lucius Van Horn to play VP Magna and change up the rules; in hopes of making some extra cash for a Mother's Day gift, Ollie rents his shed to bounty hunters Andre and Bev.
Ollie and monster gut slug, Jeffrey, team up to help each other win an eating contest and find love; after Ollie's mom sells his beloved preschool toys at a yard sale, Ollie and CW investigate the suspected buyers.
Ollie and his friends save VP Magna from beautiful monster Buene Brillo, who pursues him for his good looks; Ollie summons a monster in hopes of helping Bernie impress Mr. Pandey with his robot at the Science Fair.
After Ollie and Captain Wowski have a spat, CW is mistaken for a stray cat and gets captured by Animal Control; preparing to meet a bully after school, Bernie finds a monster device in CW's closet that can help him.
After Ollie, Cleo and Bernie use an age-up monster to get into the movies, Bernie experiences the joy of being old; Ollie impresses the coolest kids in School but now he’s got to watch a scary movie featuring his biggest fear, geese.
Ollie offers a monster realm condiment for his hot dog stand, accidentally causing weird side effects; Ollie and his classmates go on a camping trip. Ollie uses the pack to avoid roughing it, attracting Andre and Bev.