“400 Days” by Chetan Bhagat introduces readers to a compelling mystery and romance that revolves around the disappearance of 12-year-old Siya. As the case turns cold, Keshav Rajpurohit, a self-proclaimed disappointment to those around him, finds himself drawn into the investigation. Siya’s mother, Alia, refuses to give up on finding her daughter, and Keshav, despite being discouraged by his own family and societal expectations, decides to help her. The story weaves together elements of suspense, human relationships, love, and the tenacity of a mother’s determination, creating an unputdownable tale that explores the complexities of life, friendship, and the unwavering pursuit of justice.