This time it's a western thriller by the author of Puppet on a Chain, The Guns of Navarone and Ice Station Zebra. Once the plot gets moving, the reader may forget the flow of banalities that support the tale -- sure, the action has its hooks, but the writing often seems wearily contemptuous of its reader. An army train carries a doctor and medical supplies from Reese City to small, cholera-stricken Fort Humboldt -- and some gold and silver bullion on to Virginia City. On board is card cheat-arsonist-murderer-gunman John Deakin, who is also a former doctor and is the captive of U.S. Marshal Pearce. With him on the doomed train are the crooked governor of Nevada and his innocent niece. Meanwhile, Fort Humboldt has been taken over by villainous Sepp Calhoun, who is secretly in with Marshal Pearce (a wrong one) and the vengeful Paiute Indians. The action mainly sticks to the rails, though the sense of riding a great old train is not strongly evoked. Deakin, the hero, is really a federal agent masquerading under all those charges. One tense moment where half the train breaks loose on a mountain and begins rolling backward at a hundred miles per hour -- but wait for the flick. Many won't.