Synopsis："It's not a pet dog, not even a dog—it might be... it might be a warrior!" said Wu Peng, a veteran and former military dog trainer, about a stray dog. Homeless and with a mysterious past, the dog's fate took a turn when it met Li Xufan, a fresh college graduate. The two formed a deep bond, and she named him "Smile." Despite the hardships of the workplace and the challenges of reality, Li Xufan never gave up her care and responsibility for Smile. After meeting Wu Peng, they worked together to protect Smile's dignity and pride, and a romance blossomed between them "because of the dog." Li Xufan began to shine in her career, while Smile, suffering from a relapse of an old illness, longed for her to take him back to the military camp where he grew up, trained, and fought. But Li Xufan was away on a business trip and couldn't make it back in time. Smile closed his eyes forever in the heavy rain.