There is a legend of a man who lives beneath the sea. He is a fisher of men. He is The Guardian." When Hurricane Katrina swept through the Gulf Coast of the US, the men and women of the Coast Guard Rescue Swimmers raced into action, plucking thousands of stranded house owners from the deadly floods. Their selfless efforts saved or evacuated an estimated 33,520 people from the most severely affected areas. First mandated by US Congress in 1984, the Coast Guard Rescue Swimmer programme is renowned in military circles as the most gruelling regime of all.

Some 50 per cent of applicants drop out, unable to meet the rigorous physical and mental demands, so that they might join the ranks of the extraordinary men and women who free-fall out of helicopters into raging seas or storm floods to save innocent civilians from certain death.

Director Andrew Davis (The Fugitive) pays tribute to these oft overlooked heroes in The Guardian, a brawny action film awash with cliches that sinks to the depths of preposterousness by the closing frames.

Kevin Costner squeezes into a wetsuit to embrace one of his best roles in years, as a veteran rescue swimmer tormented by the ghosts of the past. He brings a touching vulnerability to the role that contrasts nicely with the cocksure swagger of Ashton Kutcher's gung-ho rookie. However, screenwriter Ron L.Brinkerhoff becomes bogged down in convention, cobbling together elements from Backdraft and An Officer and a Gentleman to drive the film relentlessly to its overwrought finale.

In the aftermath of a tragic accident during a massive storm, venerated swimmer Ben Randall (Costner) is suspended from active duty in Kodiak, Alaska. Instead, he is offered a teaching post hundreds of miles away at "A" School, which is responsible for finding the strongest and most courageous swimmers to fill the ranks. Ben begrudgingly heads south and is immediately drawn to cocky champion swimmer Jake Fischer (Kutcher), whose bravado masks a tragic secret. At first Ben and Jake fail to see eye to eye, but as the weeks progress, mentor and protege grow closer, the latter drawing inspiration from the older man's words of wisdom. "Save the ones you can Jake. The rest you've got to let go . . ."

Made with the full co-operation of the Coast Guard, The Guardian gives some idea of the extreme bravery of the rescue swimmers but Brinkerhoff's screenplay overplays the emotion, and contrives a denouement that shamelessly tugs the heart-strings. Costner and Kutcher affect their best meaningful stares in their wetsuits but their performances are frequently lost amid the well orchestrated, waterlogged action sequences.

Romantic subplots for both men - Jake woos a pretty schoolteacher (Melissa Sagemiller) while Ben wrestles with his feelings for his estranged wife (Sela Ward) - are unnecessary, and drag out the running time well past two hours.

Takashi Shimizu's follow-up to the American remake of his own celebrated horror opus bears little resemblance to the Japanese sequel Ju-On 2: The Grudge. The story line of The Grudge 2 is completely different, employing a confusing multi-layered narrative to delve deeper into the back-story of vengeful long-haired spirit Kayako (Takako Fuji) and her son Toshio (Ohga Tanaka), whose violent deaths in a Tokyo house give birth to the malevolent curse. Sarah Michelle Gellar reprises her role as care worker Karen Davis, who endured the full force of The Grudge in the first film.

In the aftermath of the blaze, Karen is confined to hospital, haunted by her hellish experience. The local police are preparing to charge her with the murder of her boyfriend, who was trapped inside the house. Back in America, Karen's bed-ridden mother (Joanna Cassidy) learns of Karen's predicament and she entreats her other daughter, Aubrey (Amber Tamblyn), to travel to Japan to escort Karen back home. At the hospital, Aubrey meets handsome photographer Eason (Edison Chen), and together they become embroiled in Karen's battle with Kayako and Toshio.

Aside from a couple of cheap shocks like Kayako suddenly emerging from a black and white photograph, The Grudge 2 fails to thrill or unsettle. Kayako, with her raspy guttural breathing and jerky physical movements, appears so frequently that she quickly loses her power to spook us, accompanied by Christopher Young's orchestral score, which opts for discordant strings at maximum volume to signal impending doom.

Performances are perfunctory - Tamblyn and Arielle Kebbel look like rabbits caught in the headlights of the plot's wild leaps of logic - and most of the characters are undernourished. Screenwriter Stephen Susco creates nothing but confusion with his criss-crossing plot that ricochets between three threads, gradually knitting them together into an unsatisfying whole. It's deliberately disorienting, and unfortunately we don't care strongly enough about the players to unravel the knots.