When we look around our homes, sheds and garages, we see an array of objects that spring to life at the click of a button. But what exactly happens when you pull the lever on a petrol lawnmower? How many individual pieces are involved in making blades spin fast enough to delicately cut your grass? In this series, James reassembles a whole host of objects which have been carefully taken apart to all their hundreds of individual component parts. Each episode focuses on one object and carefully puts it back together, screwing every screw, tightening every bolt and vigilantly rebuilding the object to its complete form, then testing its competency having gone through the process. As well as learning the history of the objects, we get a history of the component parts. As James rebuilds an engine, he explains the cylinders, what they are, how they came about and what they do. He highlights interesting and significant parts of the reassembly, pin pointing key components that are not only used in other objects, but how and why they are needed.