Ex-cleaner Ronan robs a ruthless mob to save his daughter, only to board the Abyss Train—a deadly survival game where every carriage is themed around one of the Seven Deadly Sins.

As the passengers are eliminated one by one, Ronan becomes entangled with Sienna, a mysterious bridal model who hides secrets of her own. After surviving betrayal, bloodshed, and impossible trials together, they reach the final carriage.

There, Ronan faces the ultimate choice: save his daughter or the woman who bled beside him. Who will he choose?