Ex-cop Callahan Garrity was more than happy to leave the Atlanta P.D. behind her to start her own business - the House Mouse cleaning service - and to indulge in a bit of freelance private investigation on the side. However, she owes too much to her former partner, Bucky Deavers, to refuse his request that she accompany him to the department's annual St. Patrick's Day bash. But the celebrating ends abruptly - and badly - when Bucky is shot during an apparent liquor store robbery while they're on the way home. Callahan is devastated - and the talk that perhaps Bucky was 'dirty' only intensifies her pain. Now, with the help of her feisty 'Mice', she's determined to find the culprit and clear her friend's name, even if it means piercing the veil of secrecy surrounding an Irish fraternal police organization that might be brewing up something far more lethally potent than green beer.