The Angels Take Manhattan. Review. Warning - Spoilers!

If there's one thing we've ever learned from Doctor Who over the years, it's that there must come a time when every assistant must depart.

Sometimes they get to blow up in spaceships.

Sometimes they decide to marry someone they've only just met.

And, for a very unlucky few, sometimes they simply vanish from the show with no acknowledgement they were ever in it.

Such an indignity was never likely to befall Amy and Rory Williams. Not when there was the chance of a good old-fashioned sob-fest to be had.

The Doctor and his two cohorts are in modern day New York when Rory finds himself transported back to the 1930s, to which it turns out he's been sent by the stone angels so they can keep sending him back in time in order to feed on the temporal energy thus created.

But he's not the only one there, as River Song's turned up in the guise of a female sleuth.

Now it seems Rory's doomed to spend the rest of his life trapped in a small room, cut off from those he loves, until the day he dies.

Rory and Amy think they've managed to free him from such a fate - their twin suicides creating a time paradox that'll poison the angels - but they fail and we end with Amy and Rory sent back in time, never to be seen by us, or the Doctor, again.

It'd be nice to say it's a heart-rending send-off but the truth is we've seen Rory and Amy either die or disappear so many times it's a relief to finally see the back of them (assuming they really are gone for good this time).

That's no slight on either Arthur Darvill or Karen Gillan who over the last couple of years have done their best with what they've been given but the truth is their constant comings, goings and complications have seriously undermined their chances of ever feeling like they really belong in the show.

There's also the problem of the manner of their departure. Somehow, just vanishing to spend the rest of their lives in another era robs us of a fulfilling sense of closure.

Compare their exit with Rose Tyler's first departure. Hers was more moving because we saw the aftermath of her banishment to another world, her face pressed against a wall, trying to sense the Doctor through it, the Doctor burning up a sun to pay her one last visit.

There was none of that human drama here, just two characters vanishing, never to be seen again, as everyone blubbed. This is the difference between Russell T Davies and Steven Moffat - Davies knowing how to wring emotion from a scenario, and Moffat lacking that same instinct.

But it's not just the fate of the Williamses that's strangely unmoving about The Angels Take Manhattan because the whole episode's more distracting than involving. A small cast - the two new characters left fatally undeveloped - and overly-familiar menace make it hard to maintain interest.

On top of that is a strange lack of style to it all. River Song becoming a cleavage-flaunting sleuth would normally inject some oomph into proceedings but, in light of the show's need to set a more serious tone than normal, it doesn't.

There was also the matter of the Statue of Liberty.

Having it revealed to be a giant stone angel's a fun idea but then nothing's done with it. Having shown up, the thing just stands around motionless even when no one - including us - is looking at it. It's also hard to believe a thing that size could stomp around New York without anyone ever noticing.

Still, whatever the episode's failings, it does mean at last we're free from the entanglements of the Williamses and, with the Christmas special set to introduce us to the new (lone) companion, hopefully the show can get back to a more straightforward structure that'll allow it to tell stories in a less cluttered manner than it's been able to in recent seasons.

I do wonder though why the tale was set in New York.

Surely it would have made more sense to use Los Angeles - the City of Angels?