The Astraeus crew returns to Eureka four years later and must adapt to a myriad of changes, including a more oppressive version of Deputy Andy.

The town huddles in a last attempt to locate the vanished Astraeus before it's too late!

Beverly Barlowe resurfaces in Eureka seeking Carter's help to free the Astraeus crew, and the rescue plan lands Carter in the crew's virtual world.

When a smart fire experiment gets out of control, Carter and team discover that the Astraeus victims may be the cause.

The crew moves forward after an ordeal and Warren's visit adds to the pressure.

Henry conducts a preparedness drill that winds up a disaster and Fargo faces a hard reality.

Carter's romantic surprise for Allison turns deadly when they're trapped in a sinking marine lab with time and oxygen quickly running out.

When Allison's genius older brother comes to meet her new husband, Carter feels the pressure of not being smart enough to measure up.

Jack and Allison's perfect honeymoon is interrupted when sabotage is discovered in Eureka. Elsewhere, Holly faces another hurdle to remain intact.

Eureka is cut off from the world by a malfunctioning experiment that threatens to eradicate the town's populace.

The people of Eureka are being kidnapped and replaced by body-doubles one by one unless Allison, Fargo and Zane can figure out how to avoid capture and save their town.

Wormholes randomly materialize around Eureka as the Department of Defense is set to shut the town.