If there's a target audience for a film about the life, times and death of Veronica Guerin, I suppose it's me. I was there a few hours after her murder at a meeting she was due to address: all around, there was wincing shock that a brilliant reporter could be shot down in Dublin (or indeed any Western city boasting a patina of civilisation) because of what she wrote and the drug barons she sought to expose. Thus her story, When the Sky Falls, delivered by John MacKenzie of The Long Good Friday, one of Britain's tautest action directors, ought to carry a particular charge. Alas, it is perfectly decent in a penny-plain way, but oddly uninvolving.

There is nothing wrong with the casting. Joan Allen (the Hi honey! from Pleasantville) is a gossamer thin but radiant, staunch Guerin - here lightly disguised as one 'Sinead Hamilton'. Gerard Flynn, Jimmy Smallhorne and Liam Cunningham fish balefully on the dark side of the Liffey. The exploration of Ireland's druggy underworld carries brutal conviction. But this is drama, not documentary, and the trouble is that we all know how it ends, so momentum drains inexorably as the beatings come and go, mere preludes to the awful coup de grâce.

We're told what happened, but not why. Why Guerin, loving mother and wife, risked everything? Why, on this rendition, her editors let her court such danger? Why she was as she heroically was? Three scriptwriters - including her friend and colleague, Michael Sheridan - can't seem to reach beyond the indomitable surface: perhaps because, even now, no one truly understands what ticked underneath.