Strange Are the Ways — Teresa Crane

It is winter, 1908, and the Shalakov family, with high hopes, are on the move from Moscow to St Petersburg, a city of gaiety, wealth and secret political activity. Anna, the oldest daughter, is a gifted musician. Fascinated by her uncle's skills as a master violin maker, she falls in love with him, threatening a family scandal. Escaping from St Petersburg through an unexpected marriage she unwittingly betrays her sister, Yelena, who is cruelly betrothed to a man who despises and abuses her.
Katya Bourlova is Anna's beautiful and ambitious cousin. Eager to experience adventure, she enters a covert liaison with a young Finnish officer, and soon finds herself involved in a dangerous revolutionary group, taking her to the heart of Finland...