Heat up your Valentine's with the Unlocked CollectionWhen Emmy starts at uni and Lizzie stays in London to take up an internship at a magazine, the best friends promise to stay in touch. Emmy entertains Lizzie with sexy stories about her new fling, Charlie, but then the correspondence gets competitive. Lizzie seems to be trying to go one-up with her own red-hot romance - and will she go too far?ABOUT THE AUTHORAli Cronin is the author of Skins: The Novel, the Girl Heart Boy books, and bits and pieces for newspapers and magazines. She has a borderline unhealthy interest in musicals (not only because she's got a thing for Captain Von Trapp. So brooding! So chiselled! So not-a-Nazi!), loves a stud (fash, not men), and loves to bake (although not bloody cupcakes). You can follow her at alicronin.com and on Twitter: 'ali_cronin