The penultimate instalment in the Harry Potter franchise is the scariest yet - but a film of real poignancy. Rating * * * * How to end the most lucrative film franchise of all time? By stringing it out for as long as possible. Thus the final book in JK Rowling's ludicrously successful series has been turned into not one, but two instalments - a delight for Potter fans and a gift to the accountants at Warner Bros.
So Part I is the beginning of the end, and director David Yates sets out his stall early. "These are dark times, there is no denying," intones a doomy Bill Nighy in the opening scenes. The wizarding world has become a very dangerous place.
The plot sees Harry (Daniel Radcliffe), Hermione (Emma Watson) and Ron (Rupert Grint) on the run from Lord Voldemort and his henchmen. They must sever ties with home - and Hogwarts - and go it alone.
Along the way, they embark on a quest to track down various things which will help them fight the evil forces - a horcrux containing a sliver of Voldemort's soul, the sword of Gryffindor, the meaning of a pendant that holds the key to the deathly hallows. Explanation of all this is provided for Potter novices, but a familiarity with the books is certainly an advantage.
Without doubt, this is the scariest Potter film so far. There are moments when even adult film-goers will be watching through their fingers - a scene in which Hermione is tortured, albeit heard rather than seen, another in which a Hogwarts teacher comes to a very unpleasant end. (And if you're scared of snakes, you might want to give this film a miss altogether.)
We also see a great deal of Voldemort, Harry's arch-nemesis, in a bone-chilling performance by Ralph Fiennes. Yates suffuses his film with a sense of dread that never dissipates.
But this is also the instalment that takes us deepest into the emotions of the central trio. When Harry visits the grave of his murdered mother and father, and Hermione casts a spell to remove all trace of herself from her parents' memories, they are scenes of real poignancy.
The most affecting scene did not figure in the book at all: Harry and Hermione dancing together in a tent to a crackling radio play of the Nick Cave track O Children. It manages to be sweet, funny and tear-jerking all at the same time.
We have watched these three growing up and their performances have never been better - particularly Grint, who gets the opportunity to do more than just play for laughs. His jealousy of the friendship between Harry and Hermione feels entirely real.
There are lighter moments too - we are introduced to the inner workings of the Ministry of Magic, where entry is gained by flushing oneself down a public lavatory. As always, it's the little details that delight: the self-filling champagne flutes at Fleur's wedding, Dumbledore's last will and testament unscrolling itself in mid-air.
The set-pieces are terrific, from the sight of seven Harry Potters in the same shot to a mid-air chase sequence in a motorcycle and sidecar that manages to detour through the Dartford Tunnel.
Returning cast members Julie Walters, Imelda Staunton and Jason Isaacs give brief but effective turns, and Nighy is a welcome addition as Rufus Scrimgeour, the curiously accented Minister of Magic.
Yates' only misstep is his focus on the trio's camping trip in the wilderness. This part of the film goes on for too long, and the shots of Harry looking pensive against a variety of admittedly stunning backdrops look more like a Visit Britain advert than the adventures of the world's most famous wizard.
Even at a running time of just under two-and-a-half hours, it feels as if Yates is cramming in as much as he possibly can. Can Part II be better than this? You'll have to wait until July to find out. But it'll be no mean feat.