One Day As A Tiger tells the story of Martin Hawkins, a brilliant young historian, who turns his back on a promising academic career and returns to the family sheep-farm in Tipperary where he finds himself at odds with his conscientious brother, Pierce. Hostile to the people around him, and secretly in love with Pierce's restless wife, Etti, Martin begins to harbour strange convictions about an adopted lamb he calls Missy. One of a flock that has been 'improved' with the introduction of human genes, Missy starts to make significant impact on Martin's imagination. When Etti starts to share these sentiments, she and Martin embark on a reckless and terrible adventure.