The money-spinning boy wizard and his friends face must work harder than ever in the film adaptation of the sixth and penultimate book of the blockbusting series.

David Yates returns to the director’s chair after the disappointing Harry Potter And The Order Of The Phoenix for the latest instalment in the magical series.

The sixth film is a marked improvement on the last outing, riding some of the same dark undercurrents as Harry Potter And The Prisoner Of Azkaban, which remains the strongest adventure in the series so far.

The gloomy tone is set from the opening sequence in the Muggle world, where three Death Eaters cause the collapse of the Millennium Bridge in London.

Younger viewers may need to hide behind their hands as Draco Malfoy stamps on Harry’s head, Katie Bell comes under attack from a cursed necklace and Bellatrix Lestrange and her cronies launch a night-time attack on the Weasleys.

To counterbalance the darkness, screenwriter Steve Kloves focuses on the frequently comical growing pains of Harry (Daniel Radcliffe), Ron (Rupert Grint) and Hermione (Emma Watson) as they fall victim to raging teenage hormones.

Thus, Ron tries to extricate himself from a scarily passionate Lavender Brown while Harry wrestles with his feelings for Ron’s sister Ginny.

As for Hermione, she tries to make Ron jealous by lavishing her affections on Cormac McLaggen.

Onto more serious business, Professor Severus Snape (Alan Rickman) is announced as the school’s new Defence Against The Dark Arts teacher to the delight of Slytherin House.

While Ron and Hermione continue with their studies, Harry spends time with headmaster Albus Dumbledore (Gambon) and a Pensieve memory device, delving into the evil Voldemort’s past.

The new Potions master, Horace Slughorn (Jim Broadbent), may hold the key.

Harry’s bitter rivalry with Malfoy comes to a head atop the Astronomy Tower, where one of the boy wizard’s friends sacrifices himself for the greater good.

Harry Potter And The Half-Blood Prince condenses Rowling’s hefty book into a mere 156 minutes, which pass at a fair lick.

Screenwriter Kloves is forced to sacrifice key scenes and amalgamate others with brief appearances by Hagrid (Robbie Coltrane), Remus (David Thewlis) and Wormtail (Timothy Spall).

Visual effects are near flawless as usual, seamlessly melded with the live action, including the welcome return of Quidditch.

The central trio continue to improve as actors, showing deft comic timing, and Broadbent makes his mark as the guilt-ridden addition to the Hogwarts teaching fold.

Director Yates marshals all of the technical elements with increasing confidence and skill but there’s still something missing: an emotional resonance that has readers of Rowling’s books in floods of tears.

Crucially, the film’s most important sequence doesn’t deliver the emotional sucker punch we’re expecting – Radcliffe cannot cry convincingly on camera.

The rallying cries of the dying minutes set the scene neatly for Harry Potter And The Deathly Hallows, which will be released in two parts in November 2010 and July 2011 respectively.

STAR RATING: ***