The Makers are invited to compete in a local STEM fair, which has prizes for the top presenting schools. Maker Sadie desperately wants to beat the team from nearby Skillby Tech. Inspired by a local sanitation workers' strike, Sadie decides to create a series of junkbots using her school's new 3-D printer. However, she comes to school to find that the printer has been sabotaged...or has it? Sadie is devastated and suspects the team from Skillby Tech. Readers will be excited to learn the truth behind Sadie's junkbots.