I'm not going to give a synopsis, as previous reviewers have already accurately done so.

As a long time Dr Who fan, (Tom Baker days!!)I sat and watched this with the children, aged 7, 5 and 3, and my 60 something mum too. Full credit to the writers/directors, as this appealed to us all! Even my youngest got the general idea, the older two followed the whole story, and the adults were kept amused with a few laughs and "in" references and jokes. The pace was excellent, as the story and characters slowly draw you in, and then take off at speed after a few minutes of scene setting. By the end of the episode the characters are pretty well established, and we are all looking forward to the rest of the series.

Well done BBC - this makes the licence worth while!