An illegitimate government now complicates efforts to save mankind from Sampson, the killer asteroid. After the discovery that President Mackenzie is still alive—but had been poisoned—Harris, Grace, and Darius are scrambling to topple the new administration of President Bennett. Meanwhile, Darius is running out of time to finalize his plans for the ark. Will there be a real future for Liam and Jillian? Will Darius, who was disqualified from his own escape plan, find another solution?

Darius, Grace and Harris join forces to prove the president was murdered. Also, Grace tells Zoe the truth.

Grace and Harris must forge an alliance when their children's lives are in jeopardy. Also, Liam presents Jillian with an unusual proposal.

Grace and Darius seek answers from the President and Harris discovers deadly secrets.

Grace narrowly escapes a deadly assassin and Darius and Liam forge unlikely alliances.

Darius and Grace are framed for murder and must escape from Russia; Liam tries to get Jillian to come back to Tanz.

Grace and Darius slip off to Russia behind Harris' back in an attempt to stop a potential nuclear conflict. Also, Liam seeks solace with Amanda.

Darius recruits Grace, Harris and Liam for a dangerous mission, and Jillian confronts Liam about his secret.

Darius tries to discover who killed his friend Lazlo; Liam discovers who's been selling secrets to the Russians.

To prove to Harris and Grace that he's not a traitor, Darius must reveal a closely guarded secret; Liam helps Jillian adjust to her new job at Tanz.

It's a race against time as Darius must accelerate his plan to stop the asteroid before the Pentagon shuts him down. Also, Grace has to make difficult decisions that could have life or death consequences for millions of people, and Liam and Jillian reunite under surprising circumstances.

Darius and Liam work to invent a theoretically impossible piece of technology to divert the asteroid, and Grace risks everything to help Darius. Also, Liam heads home to Boston to track down critical research, but finds something shocking instead.

When MIT grad student Liam Cole discovers an asteroid is set to collide with Earth in 186 days, he joins forces with tech billionaire Darius Tanz and the U.S. government to try and stop it – and together they stumble onto the greatest conspiracy never told.