The fifth series of phenomenally-successful BBC cop drama Line Of Duty returned to our TV screens last night, once again driving fans wild with a host of twists and shock revelations.
More than seven million tuned into Jed Mercurio's acclaimed crime show to see police anti-corruption unit AC-12 once again taking on their greatest foe, the elusive Balaclava Man.
Vicky McClure , Adrian Dunbar and Martin Compston all returned to their roles as the crack team tasked with bringing down dodgy coppers, while McClure's This Is England co-star Stephen Graham popped up as their hardest, most deadly foe yet.
Or did he?
Here are all the questions we want answered so far... (WARNING - SPOILERS)
Where have I seen the actress playing PC Jane Cafferty before?
Ambushed by gun-toting masked men in the opening scene, PC Cafferty will have looked familiar to fans of Wales-shot dramas like the Beeb's Requiem and Hidden on S4C.
Glanaman-born Sian Reese-Williams also starred in Emmerdale for years, playing Gennie Walker.
But the biggest question here is whether she had anything to do with the attack - after all, it was her who ordered the police convoy to stop in the first place, thus making them sitting ducks.
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Just exactly how long has Stephen Graham's John Corbett been undercover?
We don't know for sure - only that he's not been in touch with his handlers on the force for several months.
So does that mean he's the same 'Balaclava Man' who AC-12 have been chasing since day one?
If that's the case, could he be the masked menace who hospitalised poor old DS Steve Arnott by throwing him down a flight of stairs in series four?
Steve's back injury continuing to trouble him in last night's episode one would definitely suggest a possible connection.
So, is Corbett really a good guy after all?
Difficult to say at this point.
Clearly he's in so deep that the line between cop and criminal has long since blurred beyond all recognition.
But that final shot of his haunted expression having just ordered the execution of PC Maneet Bindra would suggest a flicker of the man he once was is still present somewhere.
What are the chances Lisa McQueen is another member of the crime gang who's undercover?
As the only gang member with an apparent conscience - she refrained from shooting dead PC Jane Cafferty in the aftermath of the opening armoured car heist - we were certainly led to believe she was the police mole.
However, the late-breaking revelation the Corbett is the cop in disguise shouldn't rule out the possibility she's also law enforcement - perhaps from another covert unit entirely, meaning she and Corbett are totally unaware of each other's true identity.
Has Ted Hastings been a baddie all along?
Living out of a cheap hotel room, saddled with a non-flushing toilet and undergoing a messy divorce, the head of AC-12's private life is truly a shambles.
Financially, it may also mean he's open to taking the odd backhander or turning a blind eye to unlawful goings-on - but surely it can't mean he's the deep cover criminal mastermind who's been pulling the strings since series one?
And if Ted isn't a wrong 'un, just who is the mysterious 'H'?
Well, that's the $64,000 question - or, in this case, £10m worth of heroin.
The end of series five saw ACC Derek Hilton fingered as the corrupt top brass in league with the bad guys - he was later found dead, having apparently committed suicide.
But, suspicions regarding Hastings aside, could Murder Squad boss Les Hargreaves be the man everyone's wants unmasked?
A long established thorn in AC-12's side, he's certainly a boo-hiss villain if ever we saw one.
And, of course, his surname start with an 'H', which is always a good start.
Line Of Duty continues on BBC One Sundays at 9pm
