Warm Nights on a Slow Moving Train (1988)

A convent teacher spreads a little happiness and makes enough money to support her crippled brother's habit by selling her favors regularly on a cross-country night sleeper. She makes sure she is in control of each encounter until one client reaches her more than she expects. As her orderly business plan turns to chaos, she is forced to commit political assassination to keep her life and her freedom, but is there another way out?