Valentine and Casper have an eventful first day on patrol as beat officers at Hambilton Green Comprehensive School when they find that a young pupil has been stabbed. Despite their initial misgivings, they discover the two boys involved used to be best friends, but soon realise that the attacker's father may have had a part to play in his son's response to the situation. Meanwhile, Nadir invites Louise Larson to look at a number of mug shots in an attempt to identify her attackers, but Louise refuses to play ball, leading Nadir to realise that something is going on between her and Smith. Perkins plucks up the courage to face his brother as he is called to give evidence against him. (thetvdb.com)