SPOILER ALERT: This article contains spoilers up to and including episodes seven and eight of the third series.

Scandinavian crime drama The Bridge, which has gripped audiences over the past five weeks, comes to an end this weekend – and fans can look forward to a killer conclusion.

Viewers and critics were thrilled when the Scandi Noir series starring Sofia Helin returned to BBC Four this November.

"How much I've missed this show," writes Ellie Violet Bramley in The Guardian. "How is it that it manages to be simultaneously bleak enough to make Lear's heath scene look like a massive LOL," says Bramley, "and yet somehow, when those opening credits roll, as comforting as a bowl of butternut squash?"

Some critics had worried about the loss of Saga's old partner Martin (Kim Bodnia), but viewers gradually got used to Henrik (Thure Lindhardt), Saga's troubled new Danish partner. Caroline Frost at Huffington Post said she was "enjoying her blossoming partnership with the equally flawed Henrik", adding that there is "a vitality to his treatment of Saga, similar to Martin but without the Labrador-eyed fondness".

For many, though, Saga is the real star. Jasper Rees on Arts Desk writes "the heart of this drama is always Saga's jagged, off-centre worldview". Helin's "eye-popping, jerky physicality and robotic speech patterns continue to be dependably weird", says Rees, adding that "the plot in which she's embroiled is as gripping if eccentric as its predecessors".

What's happened so far?

The series has seen Saga and her partner Henrik investigating a macabrely "creative" serial killer who stages complicated tableau-style murder scenes and at first appeared to be targeting lesbian and gay activists. Things became complicated when Saga's boss and father-figure Hans was also kidnapped by the killer. He was found barely alive and lingered in a coma until his life support machine was switched off.

Saga is now at the mercy of her new, unsympathetic female boss, who doesn't understand her eccentricities. To complicate matters, Saga's toxic mother made a brief unwelcome appearance after 20 years, unsettling her hard-won and tenuous peace of mind. Things got worse when Saga's mother died suddenly and Saga became a suspect in an internal affairs murder investigation.

Saga has also become involved in a relationship with her Danish partner Henrik, who has been suffering some form of post-traumatic stress, which caused him to see his wife and children, even though they disappeared years ago. Henrik not only sleeps with Saga, but admires her detective skills enough to ask for her help solving the cold case.

What can fans expect from the conclusion?

"At its core, this series of The Bridge has been about families", damaged, unhappy families which torture rather than nurture, says Alison Graham in the Radio Times. Episodes nine and ten will play out these themes to their conclusion.

Surrogate mother Jeanette is about to give birth to Freddie's child, but has just been kidnapped. The net is closing on the killer, but will they manage one last atrocity?

In the end, it's still all about Saga, says Graham. "And she will break your heart."

Will there be a Series 4?

Hans Rosenfeldt, the creator and writer of The Bridge, says that the current third series could be the last.

"It's hard to say, I actually think three seasons is quite good," the writer told the Radio Times. Many series go on for too long, said Rosenfeldt. "The Killing did three, Borgen did three, Denmark has a history of making successful crime shows in threes."

Rosenfeldt added that he would certainly not make another series of The Bridge if his female lead, Sofia Helin, pulled out. "We managed to stay alive losing one of our main characters. It would be hard to lose the other one."

The Bridge returns: Saga welcomed back in series 3

23 December

Scandinavian detective drama The Bridge has returned to the BBC for a third series after losing one of its leads – but critics still love Saga.

The Danish-Swedish co-production, created by Hans Rosenfeldt, features cross-border crime stories involving cooperation between Danish and Swedish police forces. The first two series of The Bridge focused on the relationship between an emotionally challenged Swedish police detective Saga Noren (Sofia Helin) and her more sensitive Danish counterpart Martin Rohde (played by Kim Bodnia).

When Series Two ended with Martin being sent to jail for poisoning his son's killer after a tip-off from Saga, many wondered whether the show could continue.

Martin has been written out of the new series, which sees Saga, alone and dealing with the aftermath of her decision. At the same time she must also solve a new cross-border crime involving the murder of a gay-rights campaigner, cooperate with two new Danish police partners, and confront ghosts from her family past.

While wondering whether The Bridge without Martin can ever be as compelling, critics still welcomed the show's return warmly.

Dark winter nights are drawing in and it must be time for some Nordic noir, says Amy Burns in The Independent. "Everything about this slick production is excellent, she says, praising its simplicity, solemn filming and even the sound techniques.

"The characters are utterly believable," she adds, and while there are numerous plots, subplots and tangents, it never strays so far as to lose the viewer.

"Welcome back Saga Noren, the Malmo detective we know and love," says Benjamin Secher in the Daily Telegraph. But can her new partner possibly replace Martin, who gave the brilliant Scandi crime drama its emotional core – warmth, humour and flawed human sexuality?

After two episodes the answer is still no, but there is plenty to distract us from Martin's absence, says Secher. Meanwhile, "Saga remains one of the most fascinating characters on TV".

OK, I'll miss Martin, says Sam Wollaston in The Guardian. The match/mismatch between him and Saga was a highlight of the first two seasons.

But his human fallibility was a downfall, admits Wollaston. Now there's a new Danish partner, with plenty of issues and secrets of his own and "plenty of potential for another fascinating working relationship too".

Andrew Billen in The Times, however, wonders about Thure Lindhardt's Henrik as a Martin substitute. "I actually preferred the dynamic created by Hanne, Saga's first partner in the two opening episodes," he says.

All sorts of jealousies and resentments were there to be resolved – and comparisons with Martin were impossible, says Billen. Nevertheless, he adds, The Bridge remains "exactly what winter Saturdays are made for".

The Bridge returns to BBC: Saga all alone in series 3

16 November

Hit Scandinavian crime drama The Bridge is returning to BBC 4 this week for a third series, but critics and fans are wondering whether it can survive the loss of one of its main characters.

The Danish-Swedish co-production, created by Hans Rosenfeldt, revolves around crime stories requiring the co-operation of Danish and Swedish police forces. The concept has prompted re-makes with cross-border British-French and US-Mexican storylines.

The first two series of The Bridge involved an emotionally challenged Swedish police detective Saga Noren (played by Sofia Helin) and her more sensitive Danish counterpart Martin Rohde (played by Kim Bodnia).

But Series 2 ended with Saga suspecting Martin of poisoning the man who murdered his son, and turning him over to the police.

Series creators had planned for actor Bodnia's character to return in the third series, but Bodnia left the show, because he was unhappy about the planned direction of his character, according to the Radio Times.

A trailer for the new series reveals Saga all alone, in her Porsche, listening to Johnny Cash, and clearly struggling without her old partner and friend Martin.

Saga is assigned a new Danish colleague, Hanne Thomson (Kirsten Olesen), who is understandably hostile to her after her treatment of Martin. The two, however, are forced to team up in order to solve the murder of a prominent Danish gender rights campaigner whose body is discovered in Sweden.

The departure of Martin, however, has prompted critics and fans to wonder how the show can continue without one of its central characters.

Brian Donaldson on The List says the big question that needs to be answered about The Bridge's third season is whether it can survive the departure of Martin.

The season starts with a scene eerily reminiscent of the recent macabre French series Witnesses, but afterwards, becomes "more itself", says Donaldson. It introduces a barrage of characters and snippets of information, so "blink or nod off for a second and you could soon be reaching for the iPlayer to work out what you just missed".

But the show also sees poor old Saga continue to struggle with the demons from her family past and a conflict between feeling remorse and righteousness over her actions towards Martin, says Donaldson.

So once you plough through the new characters and information, The Bridge's third instalment "looks like being another compelling addition to the north European crime canon".

And in a final note of hope for die-hard Martin fans, in a recent interview Helin (Saga) refused to rule out a potential return for Bodnia in the future, saying: "Yeah sure, why not? We have all the possibilities in the world."

Martin is in jail, admits Helin, "but what happens when he gets out?"

The Bridge airs on BBC 4 this Saturday at 9pm.