In "Snowpiercer" Season 4, Episode 9, titled "Dominant Traits," the stakes escalate dramatically as the residents of New Eden prepare for an all-out confrontation against Dr. Nima Rousseau's forces. The episode opens with Alex Cavill facing a moral dilemma as she is coerced into sabotaging the track switch computer, a decision that could either betray her allies or save her mother, Melanie. The emotional tension is palpable as Andre Layton and his crew strategize to protect Big Alice, the train that symbolizes hope and survival.

The narrative explores themes of loyalty, sacrifice, and the struggle for power, culminating in a fierce battle that pits the underdogs of New Eden against a better-armed enemy. Characters like Bess Till and Ruth Wardell showcase their resilience and determination, embodying the spirit of unity against oppression. As the episode unfolds, viewers witness intense confrontations, emotional reunions, and the looming threat of extinction. With Melanie's fate hanging in the balance, the episode sets the stage for a climactic showdown, leaving audiences on the edge of their seats, eager for the series finale.