Radon & The Telltale Trilobite

This second book of the Radon Trilogy finds Radon Schneider, pilot and geologist, flying a sortie above the Colorado River to do aerial photography. He witnesses a horrific explosion on the interstate bridge near Yuma. Working with the FBI he finds a clue to identifying and locating the culprits—a telltale trilobite, an image of a fossil on a bumper sticker. He survives treachery and gun fights, but will his scientific sleuthing prevent another bombing?