In this volume, meet Bea, Archie, Trudy, and Spence, otherwise known as the BATS! They crisscross the globe using every type of bridge: beam, arch, truss, and suspension. From ancient low-slung rope bridges to modern high-tech towers of steel, they'll traverse 'em all. Along the way they'll identify the dangerous forces trying to bring bridges crashing down, and how to defeat them... through engineering!