Katy Perry: Part of Me

A year in the life of the record-breaking pop sensation comes under the microscope in this revealing documentary, which celebrates the singer's achievements while also examining the downside of fame. For an officially sanctioned star portrait it's surprisingly honest, with Perry speaking candidly about her strict religious upbringing and the frustrations and failures of her early career, as ever- present cameras record the fallout of her crumbling marriage to Russell Brand. Directors Dan Cutforth and Jane Lipsitz use plenty of archive footage and intimate behind-the-scenes access to contrast with the cartoon-like concert sequences (which look spectacular in the 3D version) from her gruelling California Dreams world tour. Perry herself, while clearly driven and ambitious, comes across as hugely likeable and witty - the consummate professional whose personal life is in a tailspin. And watch out, too, for a wonderful cameo from her straight-talking grandmother.