The Stone Roses, Franz Ferdinand, The Strokes, Terence Trent Darby, Guns n Roses: they're all giants that have fallen victim to difficult second album syndrome and Broadchurch was their televisual equivalent, a strong opening series giving way to a fairly dull court-based second series which suggested the concept had run out of steam.

It's been two years since we were underwhelmed by Joe Miller's court case which left a Dorset community reeling but the rest of us wondering if writer Chris Chibnall could deliver something a bit more gripping for series three: this question was answered on Monday. Yes, he could.

The first episode of the third and final series began with an acting masterclass from a trio of fine actors – in particular Julie Hesmondhalgh's compelling and heartbreaking performance as Trish.

We watched the aftermath of a violent sexual assault and the way that Wessex Police force dealt with the unfolding horror, trying to soften the edges of a clinical and necessarily intrusive investigation with sympathy and support.

DI Alec Hardy (David Tennant) and DS Ellie Miller (Olivia Colman) arrived at the police station at night to find Trish outside, struggling to find a voice, her injuries apparent as she walked towards the car that would take her to the rape crisis suite. As ever with Hesmondhalgh, her face told her harrowing story without words - she didn't speak until eight minutes into the drama and I didn't notice: that's how good an actor she is.

The audience was left in no doubt about the effect that the attack has had on Trish, who was almost catatonic and unable to answer simple questions such as why it seemingly took her 48 hours to report an attack that happened at her work colleague's party – but her halting interview matched what was a slow-burning, tense episode.

We discovered that she had been hit over the head at the party and her hands bound with twine, that the attack had taken place near running water and that the attacker had used a condom: 'Trish's attacker went to that party intending to commit rape which means we have a sexual predator,' said Hardy, 'it was definitely pre-meditated.'

As Trish was preparing to be taken home to her empty bungalow, she was asked if she had any questions: 'Do you believe me?' she asked. Hardy's response didn't miss a beat: 'yes' – probably the most important piece of dialogue in the entire hour.

As we have come to expect with Broadchurch, there were clues all around us with plenty of characters carrying TV crime signposts: mechanic Jim Atwood who arranged Cath's party is the shadiest with his glove box condoms while one of Trish's neighbours and farm shop owner and Trish's boss Ed (Lenny Henry) were a bit suspect, but this has always been Broadchurch's strength: sending its audience away with questions.

They include: is Mark and Beth's separation linked to his decision to write a book about Danny's murder? Would Lenny Henry agree to a tiny cameo if it didn't eventually lead to him being pivotal? Who's the chap in the red car? Was Hardy's safety advice to his daughter (and why is she living with her father?) horribly portentous? Where is Trish's husband? Who collected the evidence in the final scene – friend or foe?

And most importantly, why is anyone still living in a village where practically everyone is either a wrong-un, a potential wrong-un or a wrong-un married to the local detective sergeant who murders children under her nose? If nothing else, it proves that even copper dream team Miller and Hardy - which sounds like an upmarket scented candle company – can't exert any authority over a town where less than 13,000 people live. Don't have nightmares.

In an incredibly strong episode, there were a few duff notes. It's difficult at this point to imagine Beth Latimer (Jodie Whittaker) being much use as a counsellor, Ellie's son Tom Miller's storyline involving him sharing pornography seemed as if it had been shoehorned into the plot to remind us of his father and while I accept that it's vital that the aftermath of Trish's attack was dealt with sensitively, several bits of dialogue felt a bit 'public sector information film'.

It's great to have a primetime drama tackling such an assault and it was handled beautifully and responsibly but there was a whiff of advice leaflet at points, particularly when the liaison officer following Trish through the reporting process gave her closing speech. It felt like the 'if you have been affected by tonight's episode of Broadchurch' helpline number should flash up immediately.

Tiny criticisms aside, Broadchurch is back to form: incredible performances, stunning camerawork, an unflinching portrayal of a difficult subject, a star-studded cast, a sinister score (from the brilliant Olafur Arnalds), some deftly-handled lighter moments and a drama so gripping that Monday nights at 9pm are now sorted for the foreseeable future. My money's on that shady booze-loving, child-clocking vicar.