There is such a thing as jusitiable violence - S1.E6

Alys, Wiliam and Ceri find the taxi driver and take revenge. The search is on for the stolen laptop, while Debbie tells Ron that she knows there are pictures of young girls on it, Toms searches the flats and threatens Kevin who wants money for returning the laptop to him. Heulwen visits her sister who she hasn't seen in twenty years, her sister turns out to be Alys' mum, but Heulwen doesn't know that it's the same Alys who lives close to her. Wiliam is told that he is invited to his daughters wedding. Shane is arrested in connection with the body found at the Chinese. Alys lends the laptop from Kevin's flat and she and Wiliam discover whats on it, Toms shows up at Alys' flat.