This review contains spoilers.

They’re never happy, TV detectives, but Marcella’s heap of woes makes the rest of these lonely, alcoholic trauma victims look like giddy little Care Bears.

Not only did Marcella’s little girl die, leaving her with regular stress-induced blackouts, but now there’s a chance the baby was killed by older brother Edward. Is that the memory Marcella’s mind has repressed all these years? This week’s episode would like us to think so. Teenage Edward squeezed his mouse to death last night, and that’s not even a euphemism. Could Juliet have been another of his victims?

No wonder Anna Friel’s character climbed up on that roof ledge. Even if her son didn’t murder her daughter, her soon-to-be ex husband has gone all daytime US soap villain and started blackmailing her for custody of their kids. He’s obviously forgotten that in Marcella, blackmail’s passed around like a plate of biscuits and she only has to blackmail him back about the town planner he had murdered in series one and he won’t have a well-tailored leg to stand on. (Marcella also appears to have forgotten that, but then she’s Marcella, forgetting stuff is her USP.)

Add to that the fact that Edward is currently being stalked by incredibly peeved convicted child molester Phil Dawkins, who’s convinced that Marcella is indirectly responsible for the death of his son in utero, and things are not looking great for our girl.

Case-wise however, it’s looking up. At least for us, if not for Edgware’s finest. We learned through Reg that Alan Summers’ alibi for the date of Leo’s disappearance doesn’t hold up. In June 2012, he wasn’t in Belgrade with the band. We also learned that those two share a secret that haunts Reg daily, and it’s not the terrible name of their band.

Most importantly, episode three let us in on some key intel that could explain the links between some of this series’ so-far distinct storylines. We’d assumed until now that the kidnapper inserting wooden discs into children’s abdomens was killing kids for his own perverse gratification. Not so. It seems that Discman (yes, it sounds a bit 80s, but what else are we supposed to call him? The Lobotomiser? Abducty McGee?) is in fact trying to help children.

He’s going a funny way about it! You might exclaim. And you’d be right. But as the old saying goes: serial killers are total whackjobs, what did you expect?

The discs discovered inside Luke’s corpse were decorated with protective symbols to ward off evil. (They clearly don’t work, else they’d have warded off the evil of being murdered by a Blue Peter lobotomy.) Discman has been inserting them into kids, lobotomising them to death, then covering their corpses in cheap toys. He meant well, apparently. In the same way someone who saws off your leg because your sock is itchy meant well.

The children Discman selects for special treatment are already troubled. Paralysed Joel has at least a serious health problem, foster-child Luke had a difficult life, little Adam was terrified of his father, and Leo had been sexually assaulted before he died. Our killer chose kids who were already victims and tried to protect them. But how, pray tell, did he find them?

Our best guess: he’s a volunteer for the Childline-alike Whitman Foundation. That would give him access to his targets’ mobile numbers, and a way to groom them. Remember little Adam hurriedly deleting that contact from his phone before his mum could find it? The next day, he’d been taken.

Speaking of which, hasn’t anybody reported Little Adam missing yet? Marcella and co., currently investigating a serial child-killer, should surely have been alerted about a local boy going AWOL. Perhaps nobody’s noticed he’s gone. That kind of neglect might explain Little Adam’s impressive resourcefulness. In some very tense scenes, and using a complex plan involving a bed spring, urination, self-harm and a blood-based lubricant, Little Adam broke free. He should definitely get a Scouts badge for that. Perhaps two.

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Not winning any badges this week was Vince Whitman, who, if he doesn’t turn out to be Discman, may at least be one of his former victims because only someone who’d had a lobotomy would think that PR stunt with the fan and the money was a bright idea. As well as a cheating, plotting wife, Vince was also revealed to have a secret past pain involving a young boxer. Does he have anything to do with our other young boxer, Angry Eric? Time will tell.

It’s hotting up, series two. The overstuffed plotting of weeks one and two is starting to pay off. And in the tense case of Little Adam, we’ve been given someone to root for other than Techy Mark (of whom we saw vanishingly little this week. Techy Mark deserves more. His own spin-off, perhaps, or at the very least a “Bouncer’s Dream” episode told from his perspective).

Will Phil hurt Edward? Will Jason move the kids to Singapore? Will Vince’s wife kill him slowly via the medium of cheese and bacon burgers? And will Joel now spell out Discman’s real name to Gail very, very slowly over the course of the next five episodes? Pen and paper at the ready.

Read Louisa’s review of the previous episode here.