Magic is real. But so are monsters. Oisin dreams of being a hero, like the ones he reads about in books. So when he overhears a plot for a midnight raid on a Dublin museum, he knows this is his chance. But Oisin soon realises that heroes must fight monsters. Dark things that lurk in the shadows - like the sinister Fomorians - don't take kindly to those who get in their way. With the help of Fionn Mac Cumhaill - yes, the legend! - can Oisin prevent death and destruction? Or will modern Dublin find itself at the mercy of the mythical monsters it had forgotten?