When an attempted robbery leaves a lieutenant dead and the entire city in a blackout, the "NCIS" team is called upon to figure out what happened -- and they are forced to use old-fashioned methods.

"It becomes a 'Barney Miller'-like '70s cop show, which none of us are particularly good at except for Gibbs [Mark Harmon], because Gibbs has got this grab bag full of '70s stuff," Michael Weatherly, who stars as Tony DiNozzo, tells ET.

The team is in the dark with no Internet, no phones, no elevator and no coffee or vending machines.

"We didn't have any computers, so we're going around with little pieces of paper and putting them on the plasma," adds Cote de Pablo, who plays Ziva. "There was a lot of McGee [Sean Murray] and Tony banter, which was really funny. Tony orders McGee around pretending that McGee is a computer and [he tries] to click McGee so that he would start talking and giving all the information."

The "Power Down" episode of "NCIS" airs tonight at 8 p.m. on CBS.