I quite liked that. It's trying to do a lot, but I don't think that's unreasonable since a Sarah Jane Adventures two-parter is a bit longer than a standard episode of Doctor Who or Torchwood. It only has a couple of missteps, to my mind. The first is some slightly clumsy handling of the theme and the second, whoops, involves the ending.

I'll start, naturally enough, at the end. One thing I'll say for this story, it's packing in the plot twists. There are two big surprises here and a few more to go with them that aren't quite as fundamental but are still worth noting. You've got the truth leaking out to people who'd previously been in the dark. There's a lot here and it should have felt epic, but unfortunately Phil Ford's hitting a reset button on almost all of it. The big twist? Nope, no long-term effect. The other big twist? Guess what. The nearest this story gets to significance in the greater scheme of things is the coincidence that Maria and her family would get written out of the show at the start of season two. Thus all the talk about "it's too dangerous for you" and "we'll have to move away" from Maria's Gay Dad is about to be realised anyway, no matter that no one involved in the show knew it while they were making this.

In other words, this story is only significant by accident. What happens in it doesn't really matter and I don't know if I'd even include it if I were citing key episodes in the series. Admittedly that's true of all of them, really, but for a while this one was looking different.

To give another point of view on this, look at the scene where Maria's Gay Dad decides they have to move. Now in fairness that's a story beat that had to happen, especially in the context of this story's theme. He's the adult. It's his job to make those decisions. If he hadn't said it, we'd all be screaming at him for child endangerment. Dramatically though, the way it's been done here is nonsense. Scene 1: "we're going to have to move away!" Scene 2: "no, I've changed my mind." What the hell is that? It's soap-opera filler to have a character say a thing and then in the next scene talk himself out of it. If you're going to make your story beat look so perfunctory, then wouldn't it have been better to put it all in the same scene and avoid the false jeopardy in the middle?

Personally I think it needed something big at the end. I don't mean the impending destruction of the Earth, by the way. It's quite an art in these things to come up with a new way of threatening terrible things in slow-motion that of course aren't going to happen. No, I think the story needed a finale that did something permanent to the show's formula and lived up to the rest of it. Mr Smith could have blown up, melted down or been infected with someone else's personality. Luke could have gone off into outer space. Aliens could have bought a house in Bannerman Road and become regulars. Okay, maybe that last one might have overloaded an already packed story, but you get the point. As it is, the aliens just drop out of the plot and go home without even a farewell scene, which we're presumably supposed to think is okay because the guy they should have murdered was in fact just "out cold for hours". The fact that by implication they've killed three people already is something we're presumably not meant to be thinking about.

Thematically it's about family, especially children and parents. This is good, but rather patchily executed. The story's doing too much to have much thematic coherence. However I did like Luke's dinosaur T-shirt, which at once evokes scientific knowledge and the hangover of dead things from the past.

The performances are okay without ever being noteworthy. Obnoxious kid is indeed obnoxious, but that's as per requirements and arguably he's the most memorable character. Floella Benjamin doesn't have a clue about what to do with her dialogue, but oddly this doesn't matter since she's such an obviously lovely person. As for the regulars, Maria's Gay Dad is too much of a face in the crowd to make much of an impact on the audience. He's just tagging along, appearing in lots of scenes without getting much to do in them. Meanwhile Tommy Knight still isn't an actor, but broadly speaking the children's performances are acceptable and Sladen's doing her usual thing. They're fine. They're doing what you'd expect of them. The important thing is that Jimmy Vee's here, making it automatically a must-watch.

One curiosity, incidentally, is that for the first time ever in this series, Daniel Anthony is being allowed to do cool things instead of simply being said to be so. It's only to the tiniest degree, admittedly, but he bunks off school and has a suitably cocky answerphone message.

Despite everything I've said, I like this story. A big story with unpredictable surprises is always good, even if I'd have been happier if all that had been leading somewhere. It's addressing the weird and slightly creepy thing about Luke being Sarah's son, which always felt slightly off to me for some reason I can't put my finger on. It has a theme. I like themes. It's also allowing things to move on with Maria's parents, which I suppose should have theoretically been the story's big format shake-up except that the credit for that is really Whatever Happened To Sarah Jane?'s. Oh, and it has returning characters, including one particularly cool cameo.

In short, it's a good, solid Sarah Jane Adventures story. What look like plot holes turn out to have explanations and it's got some nifty ideas like what happens to Clyde. It's only the fact that this has been such a surprisingly strong series that's stopping this from looking better. In another show, this could easily have been the highlight of the year.