When the team are called to a flat, they discover three children all dead with a fourth named Callum fighting for his life, DI Ross then discovers the dead body of the children's father Pete in the bathroom, he therefore becomes the prime suspect but then when forensic tests reveal that Pete died before his own children. The real culprit is still at large and shocks all of the team.

When a busker is fatally stabbed in Glasgow city centre, the newly promoted DI Jackie Reid heads up the investigation. Mita Rahim joins the Maryhill CID team properly while DI Ross suffers a personal heartache.