Oh look, it's team OAP, ready to save the world and be easily duped. Doh!
(The) Rani's mum is working late because Sarah Jane's old enemy, Mrs Wormwood of the Bane, who created Luke, wants a rush order of flowers. Except she really just wants to kidnap (the) Rani's mum and leave a clue for Sarah Jane as to her whereabouts. When Sarah Jane tracks her down, she's being hunted by the Bane and wants Team Sarah Jane's help to track down an ancient artefact that the other Bane - who now want to eat her for her failures - are chasing after. This will give them power over the entire galaxy and Wormwood doesn't want that to happen.
The problem is that the secret artefact is really in UNIT's vault of alien stuff that We don't need to know about, the Dark Archives (somewhere on a Slough trading estate, apparently), protected by maximum security (or at least some CCTV cameras and a swipe card), so Sarah Jane needs the help of an old friend to break in to get it. Together with the Brigadier - for it is he - she and (the) Rani manage to steal the artefact.
But back at home, the Bane are trying to break into Sarah Jane's house, where Clyde and Luke are hiding. Fortunately, junior Team Sarah Jane are saved by Mrs Wormwood and that pesky Sontaran we met at the start of the series, who together are really after the artefact for their own purposes.
Was it any good?
Erm, not especially. At first sight, it seems quite fun, but it doesn't take much thinking to realise it's all a bit dopey, really. Why spend so long kidnapping (the) Rani's mum and getting her to make some bouquets of flowers, when Mrs W could have just drugged her and taken her out the back days previously? Why does Sarah Jane so readily trust Mrs Wormwood, even if she does save her from the other Bane? Why is UNIT security so arse (Okay, don't answer that one)? Why is the Sontaran working with Mrs Wormwood, rather than the other Sontarans? Why do Clyde and Luke just get to sit around yapping to each other for most of the episode?
And so on.
It's really just an excuse to have a Journey's End reunion of old friends and old enemies. The highpoint of the episode is of course the return of old Who stalwart The Brigadier, last spotted (or should that be future-spotted?) having to endure Battlefield, a Sylvester McCoy story. Suffice it to say, The Sarah Jane Adventures is a step up from that.
But he's not used very well at all. He's just a bloke Sarah Jane knows who used to work for UNIT. Yes, he can mention Zygons and Daleks, but there's nothing really Brigadierish about him here and there's no time for Sarah Jane and the Brig to reminisce about - or even mention - the Doctor before the plot moves them along to that Slough trading estate. He might as well be the sonic lipstick for all his worth at the moment.
On the whole, far more about spectacle than coherent logic or depth. But it's a Who finale, so that's pretty much par for the course these days. Let's see how it all ends up next week.