Baldur's Bones. By Mary Arrigan. HarperCollins. £3.99 in UK

Tipperary author Mary Arrigan has produced a real winner in this tightly constructed, perfectly paced thriller for confident readers. When Finn and Tara discover a grisly skull on the site of an ancient Viking burial ground they are thrown into a nightmarish adventure involving the ghost of a Viking warrior, bones, relics and an army of enchanted rats. The scenes featuring the horrific rodents of Cluain na nGall are genuinely frightening. Tara is a delightfully strong and effervescent character, a good foil for the recently orphaned Finn, who is sullen and introverted. "You're wired to the moon," says Finn. "Yes, but isn't it more fun than being wired to a black cloud?" she retorts. An award-winning author, Arrigan writes in a fluent, quietly confident style, which is a pleasure to read.