The Informer is a novel by Liam O'Flaherty, first published in 1925. Set in Dublin during the Irish War of Independence, the story revolves around Gypo Nolan, a former member of an Irish revolutionary group who has fallen on hard times. Desperate and destitute, Gypo betrays his friend and comrade, Frankie McPhillip, to the British authorities for a reward of twenty pounds. Frankie is subsequently killed, and Gypo's guilt and paranoia begin to consume him as he tries to navigate the dangerous and politically charged environment of Dublin. The revolutionary group, led by the cunning and determined Dan Gallagher, begins to suspect that there is an informer in their midst and launches an investigation to uncover the traitor. As Gypo spends his reward money and tries to evade suspicion, he becomes increasingly isolated and tormented by his actions. The novel explores themes of betrayal, guilt, and the moral complexities of loyalty and survival in a time of political turmoil. O'Flaherty's vivid and atmospheric prose captures the tension and desperation of the characters, making The Informer a powerful and thought-provoking read.