The Train Robbers is a 1973 Western Technicolor film starring John Wayne, AnnMargret, Rod Taylor and Ben Johnson. The movie was written and directed by Burt Kennedy.
After the death of her husband, Mrs. Lowe AnnMargret wants to tell the railroad where to find the half million U.S. dollars in gold her late husband, Matt, stole during a train robbery, and clear the family name for her son. Instead Lane John Wayne convinces her to retrieve the gold so she can collect the 50,000 reward offered by the railroad for its return. Lane lines up some old friends to assist him in retrieving the gold for a share of the reward. But the other original train robbers have gathered a gang and will try to get the gold at any cost. As they all journey into Mexico in search of the hidden gold they are followed closely by Ricardo Montalbans character, a Pinkerton agent.After a series of adventures amp battles they return to Texas with the gold where there is one final battle. The next day Lane and his men put Mrs. Lowe on a train to return the gold and tell her she can keep the reward for herself and her son. As they are walking past the end of the train they meet the Pinkerton Agent who tells them, as the train is pulling out, that Matt Lowe was never married and that Mrs. Lowe is really a whore named Lilly who fooled them into helping her get the gold for herself. Lane then leads his gang to rob the train as the film ends. ........
Source: Wikipedia