In the "Scientific Scrubbery" there is rivalry between the head rubber and the engineer. The hand of the cashier is the prize for which they plot and counterplot. The engineer lets the mercury race up and down the tube, and the patrons fry and freeze while he lingers at the desk, until the rubber throws him bodily to the Stygian regions below. Even the proprietor, Prof. Steamem, is against the engineer, so he plans revenge. An Englishman is wandering about the dormitory when he is seen to have a black hand imprinted on his back. The patrons thinking the Mafia is after the place, run in all directions through the plant, even alarming the women and adding them to the chase. At the same time, the engineer pops a safety valve to give the effect of a bomb, and this adds a few feet to every jump they make. Bringing up in the engine room, they find that the engineer had caused all the trouble. They chase him out and leave the chief rubber and the cashier in each other's company. The "Scientific Scrubbery" is in peace again.