An Inexorable Mountie: Adventures of the First Woman Mountie. Book 7

RCMP Corporal Alexandra Houston sets out on a cross-Canada train journey to look for security vulnerabilities in advance of an upcoming VIP trip. At least, that's her cover assignment. In reality, Alex, Silver - her police-service-dog partner - and colleague Const. Jack McDonald, are after bigger game. Against a backdrop of beautiful, constantly-changing countryside, Alex notices some strange behaviours on the part of several of her fellow passengers. As her journey continues from Canada's Atlantic Provinces, through Central Canada, and then westward across the Prairies, the behaviours resolve into break-ins, intrigue, and a growing certainty that quite a few people on the train besides herself are not who they seem to be.