As the Achaia close in, the crew moves quickly to create a new weapon and save Earth. The time has come for the heroic to make the ultimate sacrifice.

After saying goodbye to her family on Earth, Niko wakes in space to find the Salvare off course and divided loyalties among her young crew.

Venturing into the ring to negotiate with the Achaia, Niko sees the unimaginable. Cas risks everything by sending Iara on a mission. Jana stuns Erik.

Under suspicion for severing a lifeline, Iara now finds her life on the line. William discovers a surprise within. A habitable planet calls to Cas.

The new planet holds promise — and unexpected threats in the brush. The tables turn as Richard reaches out to Iara. The Achaia open up to Erik.

Eager to go home by any means necessary, Niko and Richard head to a planet with an artifact. Erik and Cas go undercover, and William brokers a deal.

As tempers fray aboard the ship, the crew suits up for an expedition to an uncharted planet. On Earth, Erik tries to decode a clue from the artifact.

Niko flies blind as she contends with a damaged ship and an onboard contagion. Renowned reporter Harper Glass hounds Erik for information.

On an expedition to a mysterious moon, Sasha attempts to make first contact with a second artifact as Niko and Cas get brutally honest with each other.

Alone at last, or not? Salvare's team faces a rough ride home — and a cautious reentry. Elsewhere, Erik tests Achaian tech, then asks for a favor.

Giving up isn't an option: Niko hatches a plan and spars with Richard. The chase is on when the crew tries to stand strong, and noises rattle nerves.

While Niko races against the clock to save her ship and crew, she remembers the first time she met Cas. Sasha fears his mental state is deteriorating.

Erik's new approach with the artifact leads to a shocking development -- and grave consequences. Sasha digs for information on the Salvare's defenses.

Shock waves hit a Salvare struggling in the aftermath of an epic act of destruction. Niko questions William's judgement as Erik looks to the Achaia.

Left behind but holding on, Niko and Cas each tangle with the Achaia in their own way. At the Salvare, the crew uncovers a key alien vulnerability.

When the Salvare finally reaches its destination, Niko and her crew are staggered by what awaits them on the surface.

In a flash, Niko and Richard's world takes a terrifying turn as they wake up in a cold, cruel trap. On Earth, the team grapples with memory gaps.

The battle for control of the ship reaches critical mass as Sasha's endgame becomes clear. Erik interrogates Harper after her close encounter.

A ship malfunction leaves Niko trapped in a state of deep sleep, where she dreams again and again about the worst day of her life.

Emotions run high during the Salvare's strange trip through a dark matter field. Sasha zeroes in on William's weakness. Erik receives devastating news.