Grace (Jennifer Finnigan) and Harris (Ian Anthony Dale) have a strong feeling that Darius (Santiago Cabrera) was the one who hacked NASA.

In sneak peeks from next week’s Season 1, episodes 4 and 5 of “Salvation,” Grace and Harris team up to find out whether Darius was really the one who stole the control of the IO Probe to prevent it from colliding with the asteroid.

In the first sneak peek from the back-to-back episodes, Grace shows Harris the text message she got from Darius a few moments before NASA was hacked in Season 1, episode 3. After reading Darius’ message, Harris, together with Grace, goes straight to Tanz Industries to look for the tech billionaire.

READ: Which book did Santiago Cabrera and Charlie Rowe read before filming for “Salvation” started?

The second sneak peek, however, reveals that Darius hasn’t returned yet to his firm since he was seen riding a chopper at the end of last episode. When the firm’s guest attendant refuses to disclose Darius’ whereabouts, Harris orders a group of cops to search the whole building. Grace, meanwhile, talks to Liam (Charlie Rowe) in secret.

“Where is he?” the Pentagon press secretary asks.

“I don’t know. I haven’t seen him since the EM Drive crashed and burned,” Liam replies.

When Grace asks if Liam thinks Darius could have hacked NASA, the MIT grad student says, “Could he or would he? Those are two different questions.”

As the police continue to search the building, Grace asks Liam where Darius is keeping the barrels of Uranium he needed for the EM Drive. Liam is surprised by Grace’s question as he reveals that the EM Drive doesn’t need Uranium.

In the last sneak peek, the authorities finally have Darius in their custody. In an interrogation room, Grace asks him if he’s the one who hacked NASA. Darius insists that he didn’t do it, saying that he doesn’t have any reason to do so.

When Grace tells him that Pentagon’s intelligence confirmed that the hack came from Tanz Industries, Darius concludes that there’s a mole at his firm. “There’s a mole at Tanz. People are in danger,” Darius says. “Grace, I need you to find out who it is. Find Salvation!”

According to the synopsis for episode 5, Liam discovers who’s been selling secrets to the Russians. And as seen at the end of the trailer for next week’s episodes, Liam appears to have shot someone. Has Liam killed the mole?

“Salvation” Season 1, episodes 4 and 5 air back-to-back on Wednesday, Aug. 2, starting at 9 p.m. EDT on CBS. Watch the sneak peeks below: