Penrod Schofield's dog Duke is so troublesome that Mr. Schofield orders Penrod to keep him tied up. Penrod tries to cooperate, but Duke gets loose, and a short time later, a dog that closely resembles Duke bites Rodney Bitts, and Duke is blamed. Penrod is brought to the police station and given a lecture, while Duke is put in the pound. Vermin, Penrod's friend, rescues Duke, but while Penrod's gang, the junior G-men, plan to get Duke out of town, Rodney appears. To keep Rodney out of the way, the boys send him across town to release a racing pigeon. On the way, Rodney witnesses a bank robbery during which an employee is murdered, and he is kidnapped by the criminals. Meanwhile, the police find Duke and take him back to the pound. Duke escapes along the way and follows the kidnappers. By accident, the gang discovers that Penrod has a double, Danny Dugan, who owns a dog that resembles Duke. Determining that it is Danny's dog who has been biting people, they convince Danny to clear Penrod's and Duke's name. Rodney manages to release the pigeon from the place where he is being held. The boys receive the message, and with the help of Danny and the police, they rescue Rodney from the gangsters. Duke is given a medal for his efforts.