The Vienna Cipher. The Two Misses Vesper, #3

A dead courier carries a message no one was meant to read. Unfortunately for the conspirators, two Misses Vesper are very good at reading what others overlook. Verity Vesper and Dinah Vesper have survived forged evidence, diplomatic intrigue, and the inconvenience of falling thoroughly in love while working as unofficial intelligence operatives. By the time they board the night train from Paris to Vienna, their partnership has never felt more certain.
Then a courier dies aboard the train. Hidden among his possessions are fragments of apparently ordinary musical notation. To Verity, an aristocratic linguist and cryptographic specialist, the alterations contain the structure of a diplomatic cipher. To Dinah, a photographer whose trained eye remembers spaces, proportions, and physical inconsistencies, the same marks become something entirely different when turned the right way.
A map. Their search carries them through Vienna's concert halls, embassies, railway offices, diplomatic salons, and political circles. A celebrated pianist possesses music she did not entirely alter herself. A railway administrator has sold access he cannot adequately explain. A diplomat is trading information. A wealthy patron is concealing correspondence of her own. Everyone has a secret. But not every secret belongs to the same conspiracy.
Behind the fragments stands Kaspar Draeven, an elegant Austrian intelligence broker who understands that governments are not the only systems with weaknesses. Relationships have pressure points too-and Verity and Dinah may have given him precisely the one he needs. Because each woman has received confidential instructions. And neither is permitted to tell the other everything. For Dinah, there must be a boundary beyond which professional secrecy cannot enter an intimate relationship.
For Verity, loving someone cannot mean betraying every confidence entrusted to her. Both positions are defensible. Both women have withheld something. And neither can solve the argument simply by declaring the other wrong. Yet while trust fractures, desire does not disappear. And the cipher is still unfolding. As apparently harmless musical alterations reveal the route and timing of an assassination, Verity and Dinah must do what they have always done best: see two different versions of the same evidence and discover the truth that exists only when they put them together.
They may be able to stop a murder. Whether they can still trust the woman beside them is another question. The Vienna Cipher is Book 3 of The Two Misses Vesper, a Victorian sapphic espionage romance series featuring an established female couple, sophisticated mysteries, European intrigue, intelligent dialogue, open-door sensuality, and two heroines whose greatest strength-and greatest vulnerability-is how differently they see the world.