As Roscoe the Rainmaker is about to demonstrate his rainmaking machine to a crowd of drought-plagued Goober County farmers, a dust storm blows through the area. After being run out of town, a battered Roscoe seeks refuge in a farmhouse, where he meets Billy, a luckless farmer. After several half-hearted suicide attempts by Roscoe, Billy agrees to accompany the rainmaker to his next job in Lima Junction, California. Just before their arrival, Lima Junction banker Henry Spencer is asked by Simon Parker, a wealthy farmer, to certify a $50,000 check that Simon and his son Orville, who is in love with Henry's daughter Margie, need in order to hoodwink other desperate farmers into investing in a phony irrigation scheme. Because Henry has been overly generous with his farm loans, however, he is unable to certify the check, and Simon threatens to have him investigated. Henry's fears abate, however, when Roscoe arrives with his "magno-magnetizer" rainmaking machine. While Billy pursues a romance with Margie, Roscoe prepares to demonstrate the machine, which draws electricity out of a crowd of people and transforms it into rain, at the town fairground. Determined to prevent Roscoe's demonstration, Simon replaces his radio announcement with one advertising a town meeting to discuss the irrigation project. When no one shows up at the fairground, Billy decides that a "big attraction" is needed and, with Roscoe's help, plans a two-train collision. After tricking a railroad manager into giving them the trains for the collision, Billy and Roscoe return to the fairground. Just as they are about to demonstrate the rainmaker, however, Billy discovers that the "magno-magnetizer" has been stolen. At the same time, the train drivers, who have just learned that an engineer has placed dynamite on the trains in order to create an impressive crash, refuse to run the locomotives. Unaware of the dynamite, Roscoe and Billy volunteer to drive the trains, which run dangerously out of control for many miles. After the trains finally return to the fairgrounds, Margie finds the "magno-magnetizer" on Orville, and Roscoe saves the town by producing the promised precipitation.