Four episodes into Broadchurch, we’ve still got a list of viable suspects as long as a pier, and all we can do is wildly gamble at who the murderer is. Yet the more stumped we get, the more entertained we become. Never before has ignorance been such bliss, made so by the continued strength of the cast’s work with Chris Chibnall’s Rubik’s Cube script.

With suspicion of Mark Latimer easing, the suspect net widens, only to become more entangled. It’s a small town and threads run close together, connected by grim stares and snippets of mysterious portentous dialogue like ‘I know what you did!’

DS Miller is still so compromisingly close to the case she can eat Sunday dinner with its participants, and as DI Hardy’s illness becomes more pronounced he too becomes entangled with the locals; his sickness kept secret by hotelier and clumsy drugs handler Becca Fisher.

This is what Broadchurch does, as a town and a show. It pulls you in and wraps you up in these people’s hidden lives of quiet desperation and unanswered questions. Lives like that of sex offender Jack Marshall (a magnificent David Bradley) who, as leader of the Sea Scouts, presumably knows his way around both a boat and how to start a fire… (hint hint).

And what of the reporter who dug up said dirt on Jack, Oliver? His telly’s gone on holiday with the bailiffs, he’s clearly in financial trouble. Did he kill Danny all so that he could write about the murder and get the big scoop his career needs? Is he using Jack’s past as distraction?

And is Susan Wright’s (or is she!) shocking threat ‘I know men who would rape you’ to Editor of Broadchurch’s local rag merely her way of protecting her secret identity, or is it tied closer to Danny’s murder? At this stage it feels like another diversionary secret. Misdirection designed to keep us obsessing over the smaller juicy small-town gossip rather than solving the grim bigger picture.

Stepping back from that picture we get to see an already impressive David Tennant excel as he gets chance to add depth to his dyspeptic Columbo. Dinner at DS Miller’s home is a beautifully constructed sequence; scripting, acting, and blocking working together to make dinner feel like a catered interrogation.

Alec, sorry, Hardy’s a troubled copper – nothing new there – but Tennant’s portrayal pulls it above the cliché of ‘policeman with a past’ to give us a flawed human we’re actually interested in beyond idle chit-chat over that second glass of Rioja. He’s another mystery for us to puzzle over.

‘Outstanding!’ he shouts, in a rare moment of enthusiasm that betrays the fact the man playing him also flew the TARDIS, ‘Outstanding!’ And, as we spin the suspect wheel again, we can’t help but agree.

Aired at 9pm on Monday 25 March 2013 on ITV.

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