CANN ES (Agencies) - "Changeling," Clint Eastwood's latest film starring Angelina Jolie, got a warm round of applause Tuesday at its Press screening in Cannes where it is competing for the top prize. The Changeling tells the story of single mother Christine Collins (Jolie) in 1920s California whose nine-year-old son Walter goes missing. Months later police turn up with a boy they say is Walter, whom Christine takes home, but she knows in her heart he is not Walter. Helped by community activist Gustav Briegleb (John Malkovich), she battles against all the odds to prove it and in doing so brings down an entire police department. Eastwood is back in Cannes vying for the Palme d'Or in spite of mixed acclaim here for his 2003 entry "Mystic River." There was confusion on Tuesday over the name of the movie, one of 22 entries in the main competition at the festival this year. It was originally titled "The Changeling" but production notes re-named it "The Exchange".