Stories about purloined letters, lost naval treaties and stolen secrets can be of various kinds and raise a range of issues. Methods of investigating the theft or disappearance of documents may differ from those employed when searching for other sorts of valuables, since the person who has lost them needs to worry about both what is in the papers and also about the papers themselves; they are simultaneously material objects and indices of information. There are also many instances in which a public, government or commercial document is placed in a structural or thematic equivalence with a private and personal one (often a recipe) in ways which encode an implicit invitation to readers to compare the relative value of the two and to ask whether the substitute is really as negligible as it appears. In a nation at war and thus likely to be subject to rationing it might be no bad thing to know how to cook, and Patricia Wentworth in particular develops the suggestiveness of swapping formulae for making things for formulae for breaking things. Recipes and other documents liable to be stolen such as dress designs, scripts of mummers’ plays and drawing paper for children can also remind us that while some forms of knowledge may be universal, others may be gendered. Finally the chapter considers bibliomysteries and argues that books about the theft of books and documents implicitly assert that they themselves matter, and also assure their readers that they and their concerns matter too.