Complex sentence: Zach clears up the misunderstanding, but accidentally unlocks "The Abominable Snowman of Pasadena"; the book opens, releasing a Yeti that breaks out of the house.
Split into simpler sentences: Zach clears up the misunderstanding, but accidentally unlocks "The Abominable Snowman of Pasadena". The book opens, releasing a Yeti that breaks out of the house.