Final answer:
Dudley Nichols based the screenplay of "The Informer" on Liam O'Flaherty's work.
Step-by-step explanation:
Dudley Nichols based the screenplay of "The Informer" on Liam O'Flaherty's work. Liam O'Flaherty was an Irish novelist and short story writer, best known for his works set during the Irish War of Independence and the Irish Civil War. His novel "The Informer" was published in 1925 and served as the inspiration for the screenplay.