Arriving on a council estate - or "EastEnders land" as Rory would have it - the TARDIS trio split up to investigate. The Doctor encounters a bewildered old lady, Amy meets two creepy girls straight out of The Shining and Rory crosses paths with throughly unpleasant landlord Purcell - but there's no sign of a terrified young boy.
Amy and Rory board a lift to visit another floor, but soon find themselves plummeting to the ground! Meanwhile, Alex receives a visit from the Doctor, believing him to be a representative from social services - in tweed and a bow-tie. Our Time Lord hero is keen to learn all about young George...
Alex fills the Doc in on his son, admitting that they even considered sending George away for professional help. It seems that the child has pantophobia - not a fear of pants, but a fear of absolutely everything (presumably including pants). Random point of interest - the similarly spelt pantaphobia means the complete absence of fear. Confusing!
Amy and Rory awake in a darkened room, with the latter particularly annoyed that he's apparently been killed - again! Technically-minded Rory is convinced that the TARDIS has "gone funny" and done a "time-slippy thing" by stranding them in the past, but the Ponds soon find that everything around them is fake and made of wood - there are doors with no doorknobs, and clocks with no hands.
The Doctor visits George, who's convinced that he's come to take him away, but the Doc just wants to chat about his favourite topic - the monsters! Turns out that George is particularly scared of his bedroom cupboard, where his parents store all the things that frighten him. As you can imagine, it's bursting at the seams.
As Alex deals with the thoroughly horrible Purcell, who arrives demanding his rent, the Doctor distracts George with a few party tricks using his sonic screwdriver, but the sonic soon picks up some strange readings from the cupboard. Alex returns and prepares to open it, but the Doctor stops him. "George's monsters are real," he says.
Alex is furious at the Doctor's apparently irresponsible behaviour, but he's soon convinced when the Time Lord delivers his most rousing speech about the terrible, powerful force inside the cupboard - it's a spiel practically tailor-made for the voice-over on a Doctor Who series trailer.
Meanwhile, Amy and Rory discover what appears to be an over-sized doll - a particularly creepy over-sized doll. Sure enough, once they turn their backs - it moves! Something sinister is afoot, and Purcell's television watching is interrupted as he's somehow sucked into his own floor.
The Doctor finally braves George's cupboard, but when he flings open the doors, it's just a regular cupboard, stuffed with toys. Suddenly, the Doctor has a brain-wave - examining pictures of Alex and his family, he can find no pictures of a pregnant Claire. Alex suddenly remembers a shocking fact - Claire can't have kids, so who EXACTLY is George? We won't find out just yet, as the cupboard doors burst open, sucking Alex and the Doctor inside.
Back in the dark, creepy house, Amy and Rory encounter a terrified Purcell, who is being chased by the sinister Peg Dolls. If they catch you, you become one of them, and Purcell is quickly transformed, while the Doctor's companions take refuge behind a locked door.
Speaking of the Doc, he and Alex are now inside the spooky house too. The Doctor quickly ascertains that they are inside the dolls' house in George's cupboard, and that a perception filter altered Alex and Claire's memories - but why? It's soon revealed that the dolls' house is really a psychic repository, with all of George's fears - the sound of the lift, flickering lights - locked inside.
Trapped, Amy decides to make a run for it with Rory, but she is captured and transformed into a Peg Doll, complete with ravishing red hair. Another Doll chases the Doctor and Alex, and with the sonic screwdriver ineffective, they are forced to defend themselves with a giant pair of pink scissors. Yes, really.
The Doctor has another revelation - George is a Tensa, an alien foster child that hatches in space and perfectly assimilates into the human race. The Time Lord appeals to George to face his fears and he opens the cupboard doors, entering the dolls' house. But George is still frightened and cannot defend himself as the Peg Dolls swarm towards him...
It's revealed that George overheard his parents talking about sending him away for help and was terrified of being rejected, spiralling into a world of fear. Thankfully, Alex is on hand and finally accepts George as his son, giving him a big old hug. With the boy's faith restored, the Peg Dolls are defeated and all is well again - Purcell's back in his flat, having been taught a lesson, and Amy becomes human once again.
George's mother Claire returns home, with no idea of what she's missed. Her son is now a beaming, happy young boy, no longer frightened. The Doctor leaves Alex, Claire and George to play happy families and the TARDIS team heads off on another journey to explore "planets and history and stuff".
But as the episode ends, we hear one last snatch of the Peg Dolls' musical refrain. "Tick tock goes the clock, even for the Doctor…" Lake Silencio - and the death of the Doctor - approaches...
• 'Night Terrors' is a solid if unspectacular follow-up to 'Let's Kill Hitler'. There's a few good scares and a few good laughs, with solid performances all round.
• In particular, Daniel Mays and Matt Smith are a great double act. The Doctor shares the majority of his scenes with Alex, and the pair are terrific fun together.
• One criticism though - it's a little obvious that 'Night Terrors' was originally intended to air earlier in this run of Doctor Who. After the events of last week, it seems odd that no-one so much as mentions Melody / River.
• You can tell that Mark Gatiss is a major Doctor Who fan. References to Daleks and Sontarans are all well and good, but it takes a real 'Whovian' to work in a mention of 'Seven Keys to Doomsday'! Good job, sir!