<Li> Elisabeth Moss as Robin Griffin, a Sydney detective specialising in sexual assault who is visiting her remote New Zealand hometown of Laketop, agrees to investigate the pregnancy and disappearance of a local 12 - year - old girl, Tui Mitcham . Her ability to empathise with Tui's circumstances is based on a horrific event during her own teenage years . </Li> <Li> David Wenham as Al Parker, an old - school and well - liked detective sergeant, based in Queenstown, who also manages a café where young offenders are given a second chance . </Li> <Li> Peter Mullan as Matt Mitcham, a Scotsman and head of the Mitcham family . The informal leader of the town, feared by the townspeople, but with a complex inner life . </Li> <Li> Tom Wright as Johnno Mitcham, Matt's estranged youngest son, and Robin's teenage sweetheart . He recently returned to Laketop after serving eight years in Bangkwang, a Thai prison, for drug possession . </Li>

Who plays matt mitchum in top of the lake