Kendall and Kylie Jenner are writing a novel.
The teenage sisters are working with co-writer Maya Sloane on a science-fiction story "set 200 years in the future" that they hope to release next summer.
Kylie (14) said: "I think we will definitely get it done with how fast [the process] is going."
Kendall (16) added to E! News: "We want to do something so different, something that we really love."
The pair first brainstormed with their manager Kris Jenner on the book and are now working with Sloane on the first in a possible series for publisher Karen Hunter at Simon & Schuster.
The book will be aimed at young adults and will feature two sisters.
The Keeping Up with the Kardashians stars are very close and are always happy to motivate each other ahead of an important engagement.
Kylie tweeted earlier this week: "aww Kylie just called me & wished me a good shoot & told me im a big inspiration in her life & she looks up to me #WhatASweetie (sic)"