Beautiful stranger (1993)

Strangers on a train. Late in 1916, a brave and idealistic Russian officer in his 20s comes to his superiors' attention when he stands up to Rasputin at a nightclub. He's asked to carry important papers from Petersburg to Stockholm by train in the dead of winter, a dangerous mission. The first-class carriage may be full of spies, and soon after the train embarks, the man in the next compartment searches Obozow's luggage. A beautiful stranger approaches him, a woman older than he, on a concert tour; a game of cat and mouse ensues with patriotism and emotion sometimes on opposite sides. Can Obozow consummate the affair, reach Stockholm, and maintain his ideals?

Unfortunately the movie Beautiful stranger is not yet available on HBO Max.