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.

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.

In order to prove to Harris and Grace that he’s not a traitor, Darius must reveal one of his most closely guarded secrets. Also, Liam helps Jillian adjust to her new job at Tanz.

While Darius works to discover who killed his friend Lazlo, he is forced to reckon with his past, and Liam discovers who’s been selling secrets to the Russians.

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

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.

Framed for murder, Darius and Grace must try to escape from Russia, and Liam tries to convince Jillian to come back to Tanz.

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

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