When Chuck go undercover in Milan, Chuck realizes the "Achilles' Heel" in their relationship, but must set personal issues aside for the mission. Meanwhile, Morgan recognizes a fatal flaw that compromises the new Buy More. Elsewhere, Casey struggles to put down roots in Burbank.

Chuck and Sarah's romantic mission is canceled with the arrival of Hugo Panzer and Heather Chandler. But Chuck grows more interested when the manipulative Heather claims to know a secret about his mom. Meanwhile, as Morgan prepares the Buy More for a huge video game release, he gets a surprise from Big Mike.

Chuck and Sarah try to become better communicators as they join Ellie and Awesome on a trip to Costa Gravas; a forbidden romance may put Morgan at odds with Col. John Casey.

When Colonel Casey's former team returns looking for him, Chuck must decide what he's willing to sacrifice in order to find his mom. Elsewhere, Morgan works up the nerve to reveal a potentially dangerous secret to Casey.

Chuck, Sarah, Casey and Morgan must stop Dr.Stanley (Robert Englund) from releasing a toxin that induces nightmares... Chuck's mother's allegiances are questioned; Lester and Jeff celebrate Halloween at the Buy More.

After their first real fight, Chuck avoids confronting Sarah by going on a rogue mission that leads him to his mom's MI-6 handler, Gregory Tuttle, and a mysterious Russian agent. Meanwhile, Ellie is on her own mission to uncover the Bartowski family's long-buried past.

Afraid that his latest setback is driving a wedge between him and Sarah, Chuck resolves to prove himself by going on a dangerous mission with the overeager Agent Rye. Meanwhile, Morgan and Casey scramble as the "Buy Morons" attempt to uncover the true identity of Greta.

Chuck, Sarah, Casey and Morgan venture into the jungles of Southeast Asia when The Belgian attempts to unravel the secrets of the Intersect. Meanwhile, Captain Awesome and Ellie try to decipher a secret left behind by her father.

It's the day after Thanksgiving and Chuck faces the most awkward of family reunions when mom comes over for dinner—along with the dangerous Alexei Volkoff. Back at the Buy More, Morgan deals with the busiest shopping day of the year as Jeff and Lester hatch their latest scheme.

Chuck tries to create a romantic getaway for Sarah while tracking down a nano-chip at a French vineyard. Lester asks Big Mike for love advice.

Sarah takes dangerous measures to help Mary Bartowski bring down Alexei Volkoff, as Chuck worries that she may be getting in too deep. Sarah, though, must enlist the help of Chuck, Morgan and Casey to complete her undercover mission. Meanwhile, Ellie and Awesome are at odds over what to name the baby.

The mission to take down Volkoff reaches a dangerous new level, while big changes loom at home. As Sarah works to free Chuck’s mom, Chuck and Morgan embark on their own mission to take down Alexei Volkoff. Meanwhile, Casey bonds with his daughter, Alex, while Ellie tries to ease Awesome’s anxieties over fatherhood.

Casey, Chuck and Sarah are sent to Morocco to rescue Roan Montgomery. Morgan plans to meet Alex's mother and Mary spends some time with her family.

Chuck surprises Sarah with her old spy team, The C.A.T. Squad, leading to a mission in Rio. As The C.A.T. Squad works to settle a score with Augusto Gaez, old secrets and grudges come to light. Back at the Buy More, Morgan fends off the advances of Carina, a former flame and frisky member of The C.A.T Squad.

Valentine's Day is interrupted when Chuck and the team are sent on a mission to England to protect a reclusive young heiress, Vivian McArthur. Meanwhile, Casey gets an offer from the mysterious Jane Bentley. Back at home, Ellie and Awesome find an unlikely solution to a parenting problem, as Morgan ponders a big move.

Chuck encourages Vivian to get in touch with her inner villain for a mission. Morgan's search for a new roommate has unexpected results.

Chuck and Sarah suspect Casey is carrying out private missions. Chuck fears the CIA's new operatives will render him obsolete. Morgan settles in with a new roommate. Awesome becomes uncomfortable with Ellie's research.

Chuck is put in charge of a top-priority mission, but his leadership skills are pushed to the limit when there is a murder in Castle. Meanwhile, Awesome takes on a mission of his own when Ellie finds an alarming new hobby. Elsewhere, Morgan's leadership is also tested when his Buy More troops wage war against Large Mart.

With the help of his old nemesis Alexei Volkoff, Chuck and the team hunt down a deadly weapon, The Norseman. In a pre-wedding surprise, Sarah springs a pre-nup on Chuck.

When Chuck and Sarah get conned out of their wedding money, there is only one man they can turn to for help -- Sarah's conman father, Jack Burton. Meanwhile, Morgan pressures Casey to face Alex's mother.

Chuck and Sarah put aside spy work to have a weekend of debauchery, but Awesome’s plans for Chuck’s big night don’t go quite as expected. Meanwhile, Ellie's investigation into her father's computer leads to a life-changing discovery.

Chuck and Sarah’s wedding prep includes one final detail: ensuring that the mother-of-the-groom makes it to the ceremony alive. Meanwhile, Morgan’s responsibilities as Best Man include his most dangerous mission yet, as he faces Vivian Volkoff. Elsewhere, Ellie tends to the last details of the rehearsal dinner and seeks help from an unlikely source.

Before he can kiss the bride, Chuck must enlist his wedding party to take down Vivian Volkoff and stop her from destroying the big day. When he turns to Alexei Volkoff for help, the CIA sends its toughest agent, Clyde Decker, to stop them.