 Paroled explosives expert Bert Nelson and his partner Paul Herrick place time bombs in vacant lots near the scenes of their planned holdups. The loud but harmless explosions create a diversion that permits them to commit their crimes quickly in the confused atmosphere and escape with few witnesses. Dan Mathews and Sergeant Williams notice a pattern developing and Dan diverts all available units to the relatively small area in which Nelson and Herrick are likely to strike. After their third robbery nets $10,000, the two thieves find a phalanx of officers converging on the area. With all main roads covered, they make a high-risk attempt to escape by trespassing onto the nearby network of dirt fire roads.