If you're tempted to pick up Vampirates, which seems to have been written on the principle that pirate books sell and vampire books sell even better, don't feel too bad. You're in the company of readers who really should know better, myself included.

The combination of bloodsucking vampires and bloodthirsty pirates promises an action-filled, swashbuckling, guilty pleasure of a read, but Justin Somper doesn't quite manage to pull it off with the panache his subject demands. Geared towards the 10-14 crowd, Vampirates: Demons of the Ocean suffers from several major defects that no amount of action can disguise.

To begin with, the plot is so incidental that it becomes an excuse for the action scenes. The book opens when orphaned 14-year-old twins Grace and Connor Tempest are tossed into the sea during a storm. Connor is rescued by a pirate ship. Grace is rescued by a ship whose residents are nocturnal, toothy and anaemic. I'll let you draw your own conclusions as to what they turn out to be.

The rest of the 300-odd pages are spent alternating between Connor's experiences on the pirate ship and Grace's more interesting discoveries on the vam-- er, other ship. Vampirates works mostly to set up mysteries for an unspecified number of future sequels to unravel, so almost nothing is explained or resolved by its end. If you want to find out more -- about the enigmatic history of the Tempests' parents, the strange, shadowy captain of the vampirate ship or why the world of 2512 has pirates with cutlasses -- you'll have to read the sequels.

Fee fi fo fum -- I smell the blood of a marketing gimmick.

It certainly doesn't help that Somper's writing is unsubtle and generally unimpressive. Take the oft-repeated vampirate shanty: "Yea, if pirates are danger / And vampires are death, / I'll extend my prayer for thee -- That thine eyes never see a Vampirate." The prose isn't much better; Somper fumbles to describe what should be vivid action scenes, producing wordy episodes that are more mildly interesting than heart-racing. His young protagonists are rather bland, too, and though there are potentially interesting side characters such as Miss Flotsam (ship's figurehead by day, flirty debutante by night), none are given a great deal of time.

That's not to say that there are no redeeming qualities to Vampirates. Both vampirates and pirates are morally ambiguous, with one obvious sneering and monologuing exception. Somper's vampirates are easily the most original element in the book, intriguing amalgamations of folklore, fantasy and invention. Grace's curiosity leads her straight into their bizarre rituals and lifestyles. Connor's adventures are more prosaic, but contain plenty of old-fashioned swordfighting and looting.

It's a quick and painless read for the pirate-obsessed reluctant reader in your life, but Vampirates sinks more than it swims. You might be better off getting your pirattitude (if not vampirattitude) from Tanith Lee's Piratica or Kai Meyer's Wave Walkers trilogy.