Fox Wife by Yangsze Choo

Some people think foxes are similar to ghosts because we go around collecting qi , or life force, but nothing could be further than the truth. We are living creatures, just like you, only usually better looking . . .

Manchuria, 1908.

A young woman is found frozen in the snow. Her death is clouded by rumors of foxes involved, which are believed to lure people by transforming themselves into beautiful women and men. Bao, a detective with a reputation for sniffing out the truth, is hired to uncover the dead woman's identity. Since childhood, Bao has been intrigued by the fox gods, yet they've remained tantalizingly out of reach. Until, perhaps, now.

Meanwhile, a family that owns a famous Chinese medicine shop can cure ailments, but not the curse that afflicts them―their eldest sons die before their twenty-fourth birthdays. Now the only grandson of the family is twenty-three. When a mysterious woman enters their household, their luck seems to change. Or does it? Is their new servant a simple young woman from the north or a fox spirit bent on her own revenge?