So, have Amy and Rory departed the TARDIS with a bang or a whimper? Well a bit of both, actually.

Thankfully, like all the best marriages, there’s much more banging than whimpering. Not for the first time during Steven Moffat’s tenure in charge of Doctor Who, marriage is at the very heart of The Angels Take Manhattan, along with love and time and the persistence of hope – arguably the central themes of the show nowadays.

There’s also the creepiness of haunted houses and the dark running through the episode like veins of black onyx in rock, River Song back with her family for a final hurrah (or rather, one last ‘Yowzah!’) and the evocative landscape of New York, all moulded into an elegy disguised as a Sam Spade-style detective story. It ought to be a classic; it almost is.

The pre-credits sequence – featuring a surprisingly splendid Mike McShane as a Gorbachevian gangster with a dubious fetish for the Angels and a private dick who meets himself, old and dying in bed, and then the Statue of Liberty, alive and snarling – is one of the best in the show’s history.

The scene immediately after, with the Doctor arsing about in present day Central Park with the Ponds while reading a book by one Melody Malone (honestly, you think he’d have noticed the name, if not the cleavage), is charming in its lightness of touch – but it’s also very sad in retrospect, because it’s the last time the three chums are together in times of carefree abandon. As soon as Rory goes for coffee, things gets grim. Everyone ends up in 1938, including the recently pardoned and chaired Professor River Song, playing detective and Angel hunter.

Even in the grasp of a pissed-off stone effigy, Mrs Who still has time to drop a few zingers (‘Just you wait till my husband gets home!’) and indulge in the usual flirty repartee with her old man when he turns up. We’ve known for a long time how smitten she is with the ageless God with the face of a twelve-year-old; what’s never been as clear is how mutual the feeling is – until now.

The tender way the Doctor mends River’s broken wrist and gently kisses the back of her hand makes the depth of his love abundantly clear – likewise his bewildered hurt at being slapped around the chops for his trouble. Matt Smith is wonderful throughout this episode, and while his most compelling moments don’t come until later, the woebegone look on his face is a tiny cameo of his prodigious talent.

He’s not the only one on top form, though. The rooftop scene in which Rory and Amy commit mutual suicide in the hope of changing time and saving their lives is possibly the best we’ve seen of Arthur Darvill and Karen Gillan, as if they’ve kept their very finest for last.

The single tear that escapes down the latter’s face, the wry stoicism of the former (‘Do you think you’ll just come back to life?’ Amy snaps. ‘When don’t I?’ Rory wearily replies), their slow-mo leap from the hotel … it’s all damn near perfect. If that had been the last the Doctor saw of his beloved bezzies, with the scene of the forlorn Time Lord in the TARDIS with River following immediately afterwards, this episode really would have been a classic.

Sadly, the graveyard sequence undoes some of the good work. It’s beautifully performed by Smith and Gillan, and hugely affecting, but the emotional power can’t disguise the baffling irrationality of the plot. Once Amy and Rory have been zapped back into the past by the last Angel, what’s stopping the Doctor going to find them?

Okay, travelling back to an earlier New York is a no-no, because of all the time distortion, but there’s nothing to stop the Ponds leaving the city and heading to Los Angeles, or Chicago, or wherever, and meeting the Doctor elsewhere – perhaps leaving a sign akin to ‘Yowzah’ on a vase or ‘Hello Sweetie!’ on a cliff to help him locate them.

Talk of creating fixed points and paradoxes can’t paper over the cracks here, and while quibbling over plot holes is usually the province of the terminally tedious, here they can’t be ignored. They detract from the power of the principals’ performances, because it’s hard to engage with a scene that ultimately doesn’t make any sense.

Yet, after all that, the ending is lovely. Unlike in the previous two episodes, the use of voiceover is very fitting, and if there isn’t a lump in your throat when Amelia Pond, the Girl Who Waited, delivers her last farewell while her younger self sits on a suitcase, eagerly awaiting the arrival of the raggedy man who will carry her off across the universe for the adventures of several lifetimes, your heart is as stony as one of those contrarily tearless Weeping Angels.

Aired at 7.20pm on Saturday 29th September 2012 on BBC One.

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