This is the Doctor Who series that most requires rewatching from beginning to end. It is emotional, poignant, political, tragic, heroic, comedic, and, to my mind, the most passionate exposition in Doctor Who's forty-five year journey.
The original Donna Noble character, in the Christmas Special 'the Runaway Bride', seemed at the time to be no more than a celeb-special with Catherine Tate playing a dumpy comic heroine with enough attitude to keep the Doctor on his toes. But, from the first episode of the fourth series (not counting Christmas special Voyage of the Damned), her character builds to be the most passionate and complex of all the Doctor Who companions.
In Episode 1, Partners in Crime, we see Donna taking things into her own hands, and eventually bulldozing the Doctor into allowing her to accompany him -- though, touchy as she is, she almost doesn't go when she thinks he is being too familiar.
In Episode 2, Fires of Pompeii, she persuades the Doctor to interfere with time by saving a family that would have died. But, unnoticed at the time, a soothsayer character tells her 'you've got something on your back'. A throwaway line, it would seem.
Episode 3, Planet of the Ood, lifts Doctor Who to a new level of political awareness, with the enslavement of the Ood brought to an end at the cost of many lives. It also brings in the bizarre apparent misunderstanding 'Doctor-Donna'.
The two-parter, Episodes 4 and 5, are more traditional Doctor Who / UNIT fare, giving us back Martha Jones, and allowing for the high comedy moment when the Doctor thinks Donna is leaving, and gives her his leaving speech, only to discover she is going home to get some things.
Episode 6, the Doctor's Daughter, had me almost in tears each time I watched it. The sharply compressed timeline makes this excellent science-fiction on its own account, but it's the revival of the Doctor's daughter _after_ the Doctor and Donna have gone, so that they don't know, which lifts this episode emotionally to new highs. But notice also, it's Donna who figures out that the numbers of the rooms are dates, and solves the fundamental paradox of the civil war in doing so.
Episode 7 is the only false note in this series, for me. Perhaps others who enjoyed it would be better placed to comment.
However, the double Episode 8-9, Silence in the Library with Forest of the Dead, is to me the undisputed pinnacle of Doctor Who so far -- better than Genesis of the Daleks from the Tom Baker years, better than The Green Death from Jon Pertwee's time, even beating the multi-award winning Blink from series 3. It's no surprise that it was written by Steve Moffat, the same writer as Blink, whose forthcoming tenure as main writer promises a golden age. Alongside the terrifying plot device, which speaks to our most basic instinctive fears of the dark, the story opens up new sides to the Doctor when we meet for the first time his long-term love interest, Professor River Song. All the strangeness of a relationship with a Time Lord is brought out when we realise that this event sandwiches the first time the Doctor ever meets her, with the last time she ever meets him. But River Song's meeting with Donna, when she tells her how sorry she is, but won't say why, really sets our thoughts moving.
Episode 10, which barely features Donna at all, could have come from almost any series of Doctor Who, before or after the revival. Although light on ideas, it makes massive dramatic sense after the emotional pinnacle of 8 and 9.
Episode 11 pushes Donna right to the front, and it's also one of the most gut-wrenching episodes I've seen. Its key moment is when the Italian family are put in a truck to be taken to a concentration camp, and Bernard Cribbins as Donna's grandfather, Wilf, cries "It's happening again". Most science-fiction series on TV have a go at at-least-one alternate history episode. Doctor Who, where the rules of time travel are so much more established, understood and central to the plot, has remarkably few of them. To see another one, you have to go back to Inferno in the Jon Pertwee era. But this is the alternate history episode to beat all others: after a time-beetle-thing climbs onto her back, Donna's history is rewritten so that she never meets the Doctor. her absence from 'the Runaway Bride' results in the Doctor's death, which means that successive catastrophes are not averted, and Britain is left in post-apocalyptic dystopia. The episode is so perfectly judged that it would rival many feature films, and I was absolutely astonished to find it was just one episode -- I could have sworn it was a double.
Powerful as it is, we discover that Episode 11 is just the precursor to the extraordinary finale The Stolen Earth followed by Journey's End. Bringing all of our favourite characters back, including the ever-menacing Davros, first encountered all those years ago in Genesis of the Daleks, it is the most extraordinary roller-coaster of accidents and reversals. For once the culmination is not 'reverse the polarity of the neutron flow', but a personal dilemma which mirrors the conclusion of Genesis... Even more extraordinary is the way in which Donna is left tragically as the only person who can never know that she saved the universe. And at that point, we understand why Professor River Song was so very, very sorry.
I was highly sceptical that Catherine Tate would make a good Doctor Who companion. How wrong I was. Coupled with the amazing presence of Bernard Cribbins, who is now more than 80, and the steadily maturing performance of David Tennant, this one gets my vote as the best series of all time.
All time yet, that is. With Steven Moffat at the helm, we could be heading for even better days.