The Spy Who Never Was by Tom Savage

In a Manhattan safe house, Nora Baron—a Long Island mother and drama teacher leading a double life as a CIA operative—meets a spymaster who offers her a top-secret mission. Nora is to take on the role of Chris Waverly, a legend in the field—literally. As Nora’s handler explains, Waverly isn’t so much a person as she is an alias, a cover name shared by several American agents throughout the world. Now, a mysterious ransom note threatens these agents with exposure and certain death.
As the new “Chris Waverly,” Nora travels to Paris to trap the anonymous blackmailer. But from the start, the mission is more dangerous than she could have anticipated. She encounters secrets and lies from her own people, and she’s stalked by shadowy assassins. From the City of Light to a remote village high in the Swiss Alps, Nora follows the trail to a chilling international conspiracy—and the shocking truth about “Chris Waverly.”