Disguised as car repairmen, Mealius and Denney get aboard the express car, overpower the express messenger and steal a valuable package being forwarded to Arlington. Helen sees the crooks jumping from the car when it stops for water at Lone Point and gives the alarm. Detectives are sent to track the thieves down. The following day Helen receives a message for the local freight to bring a broken car from a mountain spur to the repair shops. While the car is being picked up, Denny and his pal, pursued by the sleuths, take refuge on the freight. The detectives search the train while it is speeding away. To prevent being captured, the crooks get aboard the broken car and cut it loose from the train. Not until the car is speeding down grade do its passengers discover the brakes to be out of order. Helen, discovering what has occurred after the runaway has passed her station, boards a locomotive standing on a siding after flashing a message ahead. The brave girl goes in pursuit of the train. Her message causes the men ahead to open the siding at Lennon. This side track runs parallel to the main track for a mile. As the result, Helen overhauls and passes the runaway, emerging to the main line ahead of the wild car. The latter is brought to a halt. Mealius and Denny attempt to escape but are halted by Helen, who holds them up at pistol's point. The two are made prisoners by railroad men and taken to jail.