Murder On The Texas Eagle — Serena B. Miller

Doreen Sizemore, an elderly Kentucky woman, is not happy that her baby brother moved to Texas. It is her strongly-held opinion that Ralph should have stayed in South Shore, Kentucky where he belongs, near her. But when Ralph begs her to come help care for his sick wife, Doreen gathers her courage and boards a train bound for Texas. After all, kinfolk are kinfolk, and no one ever accused Doreen Sizemore of not doing her duty.
Riding on the train isn't quite as bad as Doreen thought. She is even beginning to feel quite the brave adventuress...until she discovers there's been a murder on the train and Doreen is certain she knows who did it.