The exposition is perfectly balanced with bloody action and muscular set-pieces.

The film's violence erupts in rare, staccato bursts, all the more horrifying for coming out of nowhere.

If it is too stylistically modest to win converts among the multiplex crowd, the film surely rewards followers of the genre.

Director To doesn't sacrifice substance to style. The over-the-top violent flourishes, more psychological than paint-the-screen-red literal, will burrow under your skin.