The suicide of her best friend, Cheng Ruying, ripples through the lives of four mothers – Fang Yuan, Jin Lu, You Xiaozhu and Ding Mumu – as they search for the truth about her suicide. This accident shatters the perfect life of full-time housewife Fang Yuan. When Jin Lu, a non-maritalist curator, is about to realize her career dream, she accidentally gets pregnant and the father of her baby is her temporary boyfriend. The four mothers bravely face up to the twists and turns and search for their initial dreams, and at the same time, they work together to reveal the truth about Cheng Ruying's death and to do justice to the dead....

Luo Ran has been investigating the death of his wife with his best friend Ning Yu. They end up getting onto a train headed for C City in order to chase female suspect Jiang Xue. The train suddenly derails mid-journey, and the hundred or so survivors find themselves transported to a ruined city with no living soul in sight, cut off from the rest of the world. The city is filled with dangers on all sides and supplies are dwindling. The survivors start dying off or disappearing one by one—a brutal game of survival begins....