Marie Belloc Lowndes 
End of Her Honeymoon [EPUB ebook] 

A young newly wed couple are on the third week of their honeymoon when they arrive in Paris. Its the Exhibition and every lodging house is at full capacity. At well past midnight they manage to secure rooms at an ancient home, although not together. The wife is given the owner’s daughter’s room (who is away) and her husband is given a room in the garret. "No worries, Darling. Its only for one night." Morning comes but her artist husband is nowhere to be found.Not only has he mysteriously disappeared but the owners deny all knowledge that he even exists, insisting that the bride arrived alone. (Goodreads)