Even when they try to relax, the Power Coders get swept up in a coding challenge! While on the way to a local park, Tommy explains to the Power Coders that his brother, Evan, is making a robot for a "battle bot" competition. Evan may know how to build a robot, but can he create the code needed to make it work? He will after the Power Coders lend him a hand. Readers will enjoy the Power Coders'' latest coding challenge, which includes a glimpse into robotics and an introduction to Arduino microprocessors, as well as a thrilling "battle bot" finish.