The Tower 3x1

DS Sarah Collins is called to the brutal stabbing of a teenager, but her investigation soon finds itself at cross purposes with a covert operation led by Kieran Shaw, who is working with Sarah's old partner Steve Bradshaw, now deep undercover. Meanwhile, Lizzie Adama is back at Farlow trying to balance her new role as a detective with family life, but her path and Kieran's are about to cross.