Lily Collins and Sam Claflin are set to star in Constantin Film’s “Love, Rosie.”

The romcom, which Mister Smith Entertainment will introduce to buyers at the European Film Market in Berlin, is based on a novel by international best-selling author Cecelia Ahern, and is set to lense in May 2013.

Christian Ditter will helm the film, which is scripted by “Calendar Girls” scribe Juliette Towhidi from Ahern’s sophomore novel “Where Rainbows End.” Ahern’s debut novel, “P.S. I Love You,” was adapted for the screen by Richard LaGravenese in 2007 and starred Hilary Swank and Gerard Butler. Ahern’s nine novels have sold more than 14 million copies across 40 countries.

Constantin’s Robert Kulzer and Canyon Creek Films’ Simon Brooks are set to produce “Love, Rosie” with Constantin’s Martin Moszkowicz serving as exec producer.

The story follows Rosie Dunne (Collins), whose plans to attend university in the U.S. with her best friend (Claflin) go awry when she discovers she is pregnant after a night out with the most popular boy in school. Over 12 years the friends’ connection remains despite the changes in their lives.