Professor Bosco, a poor flea trainer, rents a bed in a flophouse. Before going to bed, he rallies his troops and once he has made sure his beloved fleas are settled for the night, the professor prepares to sleep the sleep of the just man. Unfortunately he accidentally knocks the box off his bed and the fleas have the time of their lives pestering Bosco's neighbors. To get the escapees back in their box again, the trainer resorts to... his whip! All is back to normal one more time. But not for long, as a stray dog enters the flophouse and very unwisely opens the box, thus creating new havoc.