It all ends,” says the poster slogan. A grim statement of the obvious, of course, yet the Potter saga could hardly have ended on a better note. With one miraculous flourish of its wand, the franchise has restored the essential magic to the Potter legend – which had been starting to sag and drift in recent movies – zapping us all with a cracking final chapter.

Here is where the Harry Potter series gets its groove back, with a final confrontation between Voldemort (Ralph Fiennes) and our young hero, and with the sensational revelation of Harry’s destiny, which Dumbledore had been keeping secret from him. The colossal achievement of this series really is something to wonder at. The Harry Potter movies showed us their characters growing older in real time: unlike Just William or Bart Simpson, Daniel Radcliffe’s Harry was going to grow up like a normal person and never before has any film – or any book – brought home just how brief childhood is.

The Potter movies weren’t just an adaptation of a series of books, but a living, evolving collaborative phenomenon between page and screen. The first movie, Philosopher’s Stone, came out in 2001, when JK Rowling was working on the fifth book, Order of the Phoenix, and when no one – perhaps not even the author herself – knew precisely how it was going to end.

The movies developed just behind the books, and it’s surely impossible to read them without being influenced by the films. This is most true for Robbie Coltrane’s endlessly lovable, definitive performance as Hagrid. In this final episode, Harry (Radcliffe), Hermione (Emma Watson) and Ron (Rupert Grint) continue their battle to find and destroy the “horcruxes” that the sinister Voldemort needs so he can stay alive for all eternity: these are objects in which the fragments of souls are trapped and whose vital, spiritual force Voldemort, that hateful parasite, can siphon off for his own ends.