Last Night's Viewing: The Riots: In Their Own Words, BBC2 Ruth Rendell's Thirteen Steps Down, ITV1

The Riots: In Their Own Words began with a clip of the Prime Minister giving voice to the national bemusement just a few days after the disturbances of last summer: "The question hangs in the air – why?" An hour later it was still hanging there, some individual answers having been offered by Alecky Blythe and Fatima Salaria's verbatim documentary, but no grand collective ones.

The method, as in Blythe's theatre works, was to use actors to voice an edited selection of interviews with rioters, replicating every intonation and hesitation – the dramatisation taking the place of the pixellation that would usually allow the guilty to speak candidly without fear of incriminating themselves.

The acting was exceptionally good, with very few of the "interviewees" displaying the betraying smoothness that sometimes mars simulated spontaneity. And Blythe's involvement seems to have ensured that the exercise would not be drearily sociological. There were moments of preserved comedy, as the earnestness of the interviewers grated against the self-dramatisation of some of their subjects. Asked where he'd gone when he heard about the disturbances, one furious man replied: "Straight to the combat zone, straight to the damage zone!" "So... do you mean Tottenham?" his interviewer said quizzically, more concerned with geography than justice.

It would have been foolish to expect very advanced powers of self-analysis from interviewees self-selected by their impulsivity, but no two explanations were exactly the same. Some claimed to feel indignation at the failure to take the protest over Mark Duggan's shooting seriously: "C'mon," said one man. "If the Queen was going to get snipered it would be a madness, you get me like? There's going to be some outcome quicker than what happened with Mark." Others, such as a middle-aged white mother (parent-governor in her local school), were moved by curiosity. She'd roped in her 14-year-old daughter to go and see what was happening and seemed blithely unconcerned that this might be seen as a dereliction of parental duty: "It was quite enjoyable," she said. "It was really enjoyable actually."

One general truth was that most people didn't see a mob on the streets. They saw their own community. And when that community started a frenzied kind of Supermarket Sweep, very few resisted the temptation to join in. "I'm getting all this free stuff," recalled a young girl, "and you're not going to get caught because there's so many people doing it." One man looted JD Sports, he claimed, "because they didn't want to recruit me when I was looking for a job." Another explained how he decided that looting from the looters would be easier than all that grubbing around on shop floors.

Shame or a sense of remorse was depressingly rare. One character claimed he felt it, but then went straight on to this: "At least I can tell my kids when I'm older, my grandkids, yeah, well, I been involved in a riot. Nice little story for them, yeah? You know, like the World War II and that, with my great-grandad?" Short on self-knowledge, certainly, but perhaps also a clue to one of the motives that lay beneath many of these accounts. They just wanted to be in a more interesting narrative, and last summer the riots gave them their chance.

Ruth Rendell's Thirteen Steps Down has a strangely chirpy set of titles for a psychological thriller, but its lead character, Mix, soon puts you right, with his creepy obsession with the serial killer John Reginald Christie. It's classic Spooky Oboe drama, complete with spectral appearances, gothic lightning and one of those "now look what you've made me do" murders. Personally, I think Danila's alarm bells should have rung when Mix put Cliff Richard's "The Young Ones" on the turntable in his eerily tidy flat. Instead, she wound him up and wound up under the floorboards.

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The Riots: In Their Own Words BBC2 Ruth Rendell's Thirteen Steps Down ITV1