Zachary Levi plays Chuck Bartowski, a low-level employee at a big-box electronics store called Buy More. Chuck is exposed to a mysterious computer program that embeds the collected espionage secrets of the CIA in his brain. As a result, Chuck becomes a government asset, handled by National Security Administration officer John Casey (Adam Baldwin) and CIA agent Sarah Walker (Yvonne Strahovski). In subsequent seasons, Chuck figured out how to use the knowledge implanted in his brain, becoming a top agent himself. He also became romantically involved with Agent Walker.
"Chuck Versus the Cubic Z" was the third episode of the series' fourth season. The episode originally aired on Monday, Oct. 4, 2010. Nicholas Wooten wrote the episode, which was directed by Norman Buckley. Guest stars included Nicole Richie ("The Simple Life") and former WWE wrestlers Stacey Keibler and "Stone Cold" Steve Austin, who reprises the role of Hugo Panzer, an operative for Volkoff Industries (owned by shady arms dealer Alexei Volkoff). Austin's and Richie's characters had appeared in previous episodes.
A truck breaks down while transporting two convicts, who are brought to the Buy More. Walker and Casey are to guard the prisoners until a helicopter arrives to take them elsewhere. The prisoners turn out to be Hugo Panzer and Heather Chandler, Sarah's former high school nemesis. While interrogating Heather, Chuck discovers she has information about Chuck's mother, who has been missing for years. Hugo Panzer escapes using only a rolled-up newspaper, and Heather reveals that he had been contracted to kill her because she quashed a $500 million deal for Volkoff Industries. Sarah and Heather escape from Hugo through an air duct, while Chuck uses one of the many self-defense techniques imprinted in his brain to escape. Sarah and Heather travel through the ventilation system to the roof. Sarah holds Heather prisoner; Chuck recaptures Hugo and takes him to the roof just as the helicopter arrives. Unfortunately, the helicopter is an ambush, filled with Volkoff Industries mercenaries. Chuck runs off to pursue Hugo, who has escaped in another air duct. Maj. Casey is shot in the leg by Volkoff's men, who demand that Sarah hand over Heather or they'll kill him. Instead, Sarah frees Heather so they can work together to take on the soldiers. After killing what they believe to be all the soldiers, Chandler and Sarah are left pointing their guns at each other.
Just then, one of the soldiers they believed to be dead aims a gun at Sarah. Heather uses her last round of ammunition to shoot him, saving Sarah's life. With no more bullets, Heather surrenders to Sarah. Meanwhile, Chuck catches up to Hugo, who knocks Chuck out simply by falling on him. Just as Hugo is about to escape, Buy More manager Big Mike stuns Hugo with a taser. Hugo and Heather, both in custody, are about to be taken away. Just then, Heather tells Chuck that his mother's code name was "Frost" and that she was very close to Alexei Volkoff.