Guest Stars Alison O'Donnell as DS 'Tosh' MacIntosh Steven Robertson as DC Sandy Wilson Lewis Howden as Sgt Billy McCabe Mark Bonnar as Duncan Hunter Erin Armstrong as Cassie Perez Julie Graham as Rhona Kelly Conor McCarry as PC Alex Grant Angus Miller as Donnie Rakie Ayola as Olivia Lennox Catherine Walker as Alice Brooks Derek Riddell as Chris Brooks Titana Muthui as Zezi Ugara John Kazek as Aaron McGuire Lorn MacDonald as Jamie Hayes Frances Mayli McCann as Niki Robin Laing as Gavin Laird Therese Bradley as Andrea Doyle Meghan Tyler as Mags Emma Mullen as Rosie Natali McCleary as Denise Amiera Darwish as PIRC commissioner