It's 1996 Dublin and Veronica Guerin (CATE BLANCHETT) is a tenacious reporter for The Sunday Dependent. For the past two years she's been covering the increasing drug trade on the city streets. Married to Graham Turley (BARRY BARNES) with whom she has a young child, she hates seeing the dealers selling their drugs to kids and has set out to expose the problem.
While that's caught the eye of local cop Chris Mulligan (DON WYCHERLEY) and Parliament member Tony Gregory (GARRETT KEOGH), she's more interested in getting the attention of those she expects are involved in the trade, including Gerry Hutch (ALAN DEVINE), Martin Cahill (GERRY O'BRIEN) and Brian Meehan (PAUDGE BEHAN). Her biggest target, however, is businessman John Gilligan (GERARD MCSORLEY) who's fresh out of prison and none too happy to have a reporter nosing around.
Despite worries from her family, including mother Bernie (BRENDA FRICKER), and a series of threats and warnings, Veronica continues on her quest and hopes to use various sources, including her shady associate, John Traynor (CIARAN HINDS), to nail Gilligan and his cohorts.