The Intruder tells the story of Tullio Hermil, who is habitually unfaithful to his loving wife Giuliana, until one day when the wife eventually does the same. Tullio is handsome, smart, and strong. He considers himself superior to other men. He is repeatedly unfaithful to his patient and innocent wife, Juliana, who tolerates his abuse and infidelity for a long time. At last, growing exhausted from his own behavior, Tullio tries to reconcile with his wife. Things take a huge turn in his life when he finds out that Juliana has gotten pregnant with another man's baby. When the baby - the Intruder - is born, Tullio begins to plan a crime that can lead to devastating results. It is a horrifyng sory by the Italian writer Gabriele D'Annunzio. The author displays his true genius in the novel with his unusual storyline that is not everybody's cup of tea, with characters that will infuriate and entertain at the same time.

Gabriele D'Annunzio (1863–1938) was an Italian writer, poet, journalist, playwright, and soldier, who left an indelible mark on Italian literature and politics. Born in Pescara, D'Annunzio manifested an early penchant for literature, composing poetry from a young age. His literary style is known for its sumptuously descriptive language, exploration of psychological complexities, and frequent undercurrents of decadence, which together define the Italian Decadent movement of the late 19th and early 20th centuries. D'Annunzio's works often delve into the exploration of the human condition, probing into themes of passion, beauty, and the pursuit of the ideal. 'The Intruder' ('L'Intruso'), while less well-known than some of his other works, nonetheless encapsulates his rich narrative approach and affinity for delving deep into his characters' psyches. Some of his other significant works include 'The Child of Pleasure' ('Il Piacere'), 'The Triumph of Death' ('Il Trionfo della Morte'), and 'The Flame of Life' ('Il Fuoco'), which not only highlight his literary mastery but also reflect the complexities of his own life. Beyond his writing, D'Annunzio's controversial involvement in politics, particularly during World War I and his subsequent establishment of the short-lived Regency of Carnaro, still sparks debate among historians and literary scholars. Viewed as a forerunner of Italian Fascism, his imprint on both literary and political history remains a subject of complex appraisal.