K. (novel)

{{short description|1915 crime novel by Mary Roberts Rinehart}}

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{{Infobox book |

| name = K.

| title_orig =

| translator =

| image = K M R Rinehart.jpg

| caption = Universal Jewel Pictures Photoplay cover art (1924)

| author = Mary Roberts Rinehart

| cover_artist =

| country = United States

| language = English

| series =

| genre = Novel

| publisher = Houghton Mifflin

| release_date = 1915

| media_type = Print (Hardback)

| pages = 410

| isbn =

| oclc = 39111410

| preceded_by =

| followed_by =

}}

K. is a 1915 crime novel by the American writer Mary Roberts Rinehart (1876–1958) set in post-Victorian era Allegheny, Pennsylvania, which has been a part of the city of Pittsburgh since 1907.

K. is a romance set in the industrial Victorian era. The novel tells the story of Sidney; when Sidney takes in a boarder with the initial "K", her life becomes entwined with the mystery surrounding "K". Lies and intrigue surround Sidney.

A film version of the novel K – The Unknown starring Virginia Valli and Percy Marmont, was released on 17 November 1924 by Universal Pictures as a "Universal Jewel" release. Another film version was released under the title The Doctor and the Woman in 1918.