Casey's employer, the Midwest & Central Railroad faces bankruptcy unless it gets a U.S. mail contract for the St. Louis to Ft. Worth run. The catch is that the company that gets the contract must win a train race. The MCRR's track runs through the Ozarks, but Casey still thinks his engine, the Cannonball, is faster than his competitor's, but the Southern & Panhandle Railroad, the rival company, sends saboteurs and gunmen to slow his progress.
After an old prospector is shot by an outlaw to steal his treasure map, Casey helps the sheriff catch the murderer, but then later discovers that the villain is the wayward son of carpenter Pete Dunlap, one of Casey's best friends.
Jones arrives at Finney's offices to be briefed by Peter Holmes a US treasury official. Jones is due to run a military prison train to Kansas and is instructed to take a load of gold bullion with him. Part way along the trip the train is stopped by damaged tracks. They decide to back the train up only to discover the line behind them is also damaged. A gun battle erupts when a group of outlaws ride in but a driven off by the guards. Casey devises a plan to rebuild the rails. The plan requires releasing the prisoners, who see their chance and make a break for it till ...
Casey and the Cannonball pull into Midvale and gets an urgent message from Mr. Carter to see him urgently. He is introduced to Bill Maguire, a secret service agent for the President who will be passing through the town the next day. Casey is then offered the job off hauling the Presidents Special out to the start line for the new territories. A second agent Charles Upton is expected in town, but is bush whacked by men wanting to kill the President. Next day Casey and the fake agent take a run on the Cannonball to go over the route to be used by the President. At ...
Casey's train is robbed by a gang of outlaws. A hostage situation develops as the criminals realize the mail they were after is not aboard. To buy time Casey tells them the next train coming through will have what they want. For the next 6 hours Casey has to play a delicate game of divide and conquer with the gang, while keeping the passengers out of harms way
Casey races a top gun coachman into Midvale where they are greeted by a US army officer who takes command of the train and coach. The army is transporting a prisoner (Geronimo) to Deadwood and explains to Casey they expect trouble from Indians on the way. At Willow Springs the train is delayed after Indians have killed all the station staff. Finally arriving at Deadwood, Casey volunteers to ride with the stage coach to Gailleville to complete the prisoner transfer. Apache war-bands have other ideas and press home repeated attacks.
Casey is shocked to see the Cannonball sudden drive off with no engineer or fireman. Despite repeated communication with other stations, the train appears to have vanished off the face of the Earth. While searching for his train Casey becomes embroiled in a scheme to move stolen gold using the hidden Cannonball; a scheme that also requires the death of Jones at the hands of someone very close to him
Due to bad weather Casey's train is canceled. Returning home he discovers two escaped prisoners have broken in and are holding the family hostage. One of the men is in desperate need of medical attention and Casey has to play a delicate game to keep his family safe while complying with the demands of the criminals
Casey pushes the Cannonball through a night of torrential rain till they are stopped by a washed out line, and Casey is forced to wait for permission to switch to another line. As the rain continues, concern grows over conditions at the local dam. Suddenly a simple passenger run has become a desperate rescue effort. The dam finally fails and Casey has to balance the needs of his passengers with those of the remaining families in the area.
Casey stops at Jamestown to discover the local dispatcher has been arrested for murder. Complications arise when it is discovered the arresting marshal is the brother of the man who the dispatcher killed.
The president of the railroad wants to see Casey urgently after a train wreck occurred during a railway strike. He is instructed to take a United States Marshall and a star witness non stop to Denver. During a run through a tunnel, the Marshall is shot. The witness explains she is aware of a gang, the Worker's 7 who caused the wreck, and they may be after her. A desperate race against time develops as Casey tries to find a bomb hidden somewhere on the train while keeping to his tight schedule
The Cannonball is forced onto a siding to allow a special silk train to pass that is attempting to run from the West coast to Chicago non stop. Unknown to Casey there are men on his train with a vested interest in seeing the train fail.
A big spender, Arlo Bradford charters the Cannoball to pick up his new bride from a nearby town . He soon falls afoul of Casey with his flamboyant ways and easy spending. Casey's suspicions grow as a series of strange events dog the trip to the point Casey is convinced the man is a criminal