Series 6 of Grace is guaranteed to be full of fireworks after that chilling cliffhanger for series 5.

Cassian’s revelation that a crime gang has Bruno in its sights is just one of a number of ongoing mysteries the show needs to pick up on next year.

And that’s not to mention a couple of dangling plots left over from series 4 that weren’t even mentioned in the latest series, which could come back to bite Roy and his team at any point.

Here’s our guide to all the unresolved plot lines that Grace needs to tackle in series 6 when it broadcasts next year.

So Grace series 6 is confirmed?

It sure is. Series 6 was confirmed in February, in fact, before series 5 had begun airing. We don't know when it will release yet but, given there were only seven months between 4 and 5, it's likely to be before 2024 is done.

Continuing fallout from Sandy’s disappearance in Grace series 6

Grace’s boss Cassian Pewe had an eventful series 5. He was the definition of ‘game-changer’ in human form.

Not only was he revealed to be a bent cop in episode 3, but he spent most of his remaining scenes in the last two episodes delivering one jaw-dropping revelation after another.

If you remember, we finished series 4 believing that Sandy had vanished because she felt “overwhelmed” and didn’t think she could turn to Roy, who was preoccupied with his career.

She was very light on actual details. Then she took her own life. Allegedly.

But in series 5 Cassian revealed more of the truth to Grace, after he had exposed him as a dirty cop.

Cassian, it turns out, was being coerced into working for Organised Crime Gang (OCG) Benchdale, run by Kamran Elin, with Roel Albazi as his second in command.

But Team Grace has been unable to pin anything on Benchdale: “Elin and Albazi are elusive and they’re smart,” said Nick. “They groom lower-tier members of the organisation to do their dirty work, making sure the evidence never traces back to them.”

So why was Cassian working for Brenchdale?

So what hold did Brenchdale have over Cassian? It was all to do with Sandy, he told Roy after he’d been busted.

(And the tale he now told parallels much more clearly the story in Peter James’s book They Thought I Was Dead, which also features Roel Albazi.)

“What is it they’ve got on you? It must be quite something,” demanded Roy, as they faced off in Brighton’s Hippodrome (which is currently under renovation and provides an eerie backdrop for the confrontation).

“I’d be careful what you wish for, Roy,” warned Cassian ominously.

He then admitted he had an affair with Sandy, who couldn’t turn to Roy because he was married to his career.

She was “gambling, drowning in debt” and owed £200,000 to Roel Albazi and Kamran Elin. They were threatening to kill her and her unborn child (another thing she didn’t tell Roy about).

“She knew she couldn’t rely on you,” Cassian told Roy. “Her only option was to disappear. So I got her a new identity. She promised she would let me know when she was safe. But I never heard from her… I had no idea what had happened to her.”

Sandy vanished to Munich without even telling Cassian where she’d gone, and he didn’t see her again until she returned to Brighton briefly in series 3. At which point, Cassian said, “Benchdale were watching,” and they tracked her back to Munich.

We learned more in episode 4, when an incarcerated Cassian summoned Roy to HMP Eastville to deliver more revelations.

“Benchdale have communicated something that affects you very directly, Roy,” he said. “They killed Sandy. Her death wasn’t suicide. They just made it look that way. They’re good at that.”

“Why should I believe a word you say?” sneered Roy.

“Albazi was sighted in Munich two days before Sandy’s death. And the car accident? I’m not sure that’s what it was. Sandy’s debt still isn’t paid. And though it pains me to say it, they know that she still has a son. Bruno.”

“So, what?" said Roy.

“So Albazi’s failure to recover Sandy’s debt led to his family getting seriously hurt. I don’t know the details, but I hear he’s out for blood. An eye for an eye, Roy.”

How will the threat to Bruno pan out in Grace series 6?

So now we have a threat to Bruno, just at the point Cleo wanted Roy to take on more parental duties for the boy.

Presumably, we’ll also be seeing Albazi next season. At the very least we're sure to hear about some of his activities if he uses underlings to try to kill Bruno.

We’ll probably also learn more details about what exactly happened to Albazi’s family and why he’s hellbent on vengeance.

Will Roy have to place Bruno in hiding?

And are there still things we might learn from Bruno about when his mum was on the run?

We haven’t seen the last of Cassian, surely?

We’re also not convinced we’ve heard the last from Cassian. The details about why he was working for Benchdale still seem very vague, and ripe for fleshing out.

For one thing, has he been doing them favours for nearly ten years, right from when Sandy vanished?

In which case, that bunch from AC 12 (well, okay, not actually AC 12, but we’d have loved it if Bella or Vee had sarcastically called them that) who swooped into East Sussex Police offices to cart away all those case files might discover countless instances of historical corruption.

Expect more revelations from Cassian to come.

Is Vee’s dad going to be important in series 6?

A new ongoing mystery also reared its head in the final episode of series 5 – what’s going on with Vee’s dad?

DC Vee Wilde is the newest member of the team, a young firebrand brought in this series to replace Norman Potting. She was quickly brought down to earth by DS Bella Moy, who then became a mentor figure to her.

Then in episode 4 we learnt a little bit about Vee’s past

While the team was investigating a double murder in Ridgeton Park, a uniform cop recognised Vee.

“Dave Cripps,” he introduced himself. “You’re James Vernon’s daughter, right? I served with him in the Met. Chapelwood nick.”

Clearly shaken, Vee told the guy she didn’t know what he was on about. “My dad’s name’s not James and he’s not a copper.”

“Really? Those barbecues at his place in Kensal Rise – that wasn’t you?" Cripps replied.

Bella interrupted, saving Vee from further discomfort, but PC Cripps was obviously not convinced.

Later we saw Vee illicitly using Bella’s password to access digital police records above her pay grade and do a search on PC Cribbs (discovering that he was demoted down to a uniform cop following complaints about his conduct) and James Vernon (who was CID until being dismissed for gross misconduct).

Vee later admitted to Bella: “I’ve just found out that he was suspected of killing an informant.”

She also said that he left when she was 16. “His drinking was off the charts so he said I’d be better off without him.”

And that seemed to be that. Until Vee’s phone buzzed at the end of the episode. It was an incoming call from her dad. Which she ignored…

To be continued in series 6, you have to assume.

Is there more to come with the investigation into Glenn’s wife?

Whatever happed to that investigation into Glenn’s nurse wife, Ari, who’s suspected of negligence and causing the death of a patient at the hospital where she works?

It was a fairly big deal for three episodes, and we were left with Glenn asking local journalist Sara Joshi for some help trying to see if there was anything fishy going on at the hospital.

Then nothing in episode 4.

We’d be surprised if this storyline doesn’t resurface next series after all that meticulous setting up.

Is there more to come on DC Nick Nicholl’s marital strife in Grace series 6?

In Grace series 5, episode 3, DC Nick Nicholl was wrongly accused of being a dirty cop. Part of the reason why was a suspicious change in his behaviour.

But the reason he’d been acting out of character turned out to be the result of a breakdown in his marriage (he’d been living in a bed & breakfast for a few weeks) and he was later fully exonerated.

So were his personal problems just a handy red herring for the sake of the episode, or will we learn more about whether he’ll ever get to see his kids again next series?

And what about two dangling plot threads that didn’t get picked up in series 5?

As we speculated in this article, we thought we might be seeing more of past villains Alvin Smallbone and Dr Crisp in series 6. They both featured in series 4, both remain at large, and both hinted heavily on screen that Grace may not have seen the last of them.

But they were conspicuous by their absence in the latest series.

So, could they be back in series 6? Stay tuned.

We’re also not convinced we've seen the last of Terry and Barbara Maxwell. It looked like he was using his solicitor voodoo to try to prevent her going to jail in the series 5 finale, so they could make a reappearance too.

Maybe Terry ends up representing Alvin? Stranger things have happened.

Which Grace books will series 6 be based on?

You might think, since the series has pretty much been adapting the Grace books in order up to now (the show shuffled the order a bit in series 5), why not just read the next four books in the series to find out what happens?

The four books in question being:

Book 17 – Left You Dead

Book 18 – Picture You Dead

Book 19 – Stop Them Dead

Book 20 – One Of Us Is Dead

(These, by the way, are all the books that have been published so far, so it’ll be interesting to see what happens if the powers-that-be commission a seventh series.)

Well you could read them and spoil yourself to an extent. But while – in the past, at least – the central crime plots in each case have been similar on screen, the ongoing storylines involving the regulars have increasingly started going their separate ways.

Plus, the background to Sandy’s storyline – as related in the book They Thought I Was Dead, is being drip-fed into the series, rather than everything coming to light in one go.

So, you could read the books, but we expect there are still many surprises in store even if you do.

All 5 series of Grace are currently available on ITVX