Castle. Morgan and Casey bicker. Casey's back to being mean to Morgan, even though he got him the job on the team. His best threatening line is, "You know it can take up to seven minutes to strangle someone? I've done it in under thirty seconds." Morgan's not that impressed, and instead makes Casey feel like a wimp for being too scared to ask for Morgan's help in finding Chuck. Morgan says he's been studying Chuck for more than twenty years so he knows a thing or two. He quickly figures out where Chuck is based on knowing he left his eczema prescription at home and would have had to fill one. That doesn't work, so they find him buying a copy of the latest issue of Justice League. Conveniently, Chuck has his destination showing on his train ticket: Zurich. Casey tells Morgan to pack, and Morgan gets all excited about traveling first class on the government's dime. Which, of course, means the next scene has Morgan and Casey crammed into coach next to someone holding a fussy baby. Casey wants to sleep, but Morgan believes he has to be awake rooting for the plane to stay aloft in order for it to actually do so. Casey puts in earplugs and tells Morgan if he wakes him, he'll be the only one who dies.
Sarah and Chuck are drinking coffee in their jammies, all cuddly the next morning (or so it seems) discussing how to take down Arnaldo and deliver him without revealing themselves. They're going to cuff him to something at the next station and call Interpol. They kiss, and Sarah wonders what the plan is, since all of their spy gear's in Paris. The plan, apparently, is for Sarah to sweet-talk a rocker and steal his handcuffs -- though those might not be for the spying so much as the sex; it's hard to tell with these two. Chuck grabs the cuffs from her and flashes on French so he can talk to a French skier with a hurt leg. He offers her a pillow and steals her painkillers. Back in their room, they get some Southern accent practice so they can fake like newlyweds for the terrorists. Chuck can't help but feel like they're missing something. Hmmm. What could they possibly be missing on a spy mission? The train stops.
CASEY and Morgan are getting on the train (that was a fast flight to Europe, wasn't it?). Casey's annoyed at Morgan's huge backpack and Canadian flag, but he's all about being a proper tourist since he's barely been out of Burbank. They split up and search the train: Morgan has sleeping compartments and Casey has the dining car. Which is where Sarah's acting like a perfectly obnoxious Southern belle. She runs over to introduce her husband to the guys whose room she barged into. The terrorists are very nice and polite, even when she spills their drink. Chuck tells them that "Mr. Charlie Charles doesn't spill a drink onto another man's cheese tray without getting him a new drink." Then he gets one, presumably to lace with the sleeping pills.
Ellie and Awesome are alone next to a Jeffster!-occupied stage in their apartment entrance. Ellie wonders why they need a rehearsal anyway, and even Awesome looks annoyed. Jeff quickly blows the amp with his piano-guitar, and he says they need Chuck to fix it. Ellie gets flustered: "No, we don't need Chuck." She tells them they'll figure something else out, so Lester sends Jeff home after their turtlenecks and says they're going unplugged tonight. He takes a big swig of his drink, which Awesome tells him is just lime juice. Back on the train, Chuck gives the terrorists their laced drinks and then steals his wife away. They leave them with a "cheers" then talk about what a great team they are before they start to kiss at their own table. Which is the perfect time for Casey to enter, disgusted: "Oh, god." He sits down, and they wonder what he's doing here and he says he's putting to rest any ideas they have of making this a permanent vacation. They fill him in quietly and quickly on the Basque terrorist, but Casey's not buying it. When the first terrorist passes out, Juan Diego gets what's going on and takes off. But Casey handcuffs Chuck and Sarah together, so they can't go after him. But they can. They punch him simultaneously with a "Sorry," and take off.
Meanwhile, Morgan's in the regular traveling car, where he sees a hottie with a Canadian maple leaf on her scarf. He asks if she's Canadian, and then says, "Me too, eh?" He asks if she's seen his friend, who's "aboot," but she cuts him off: "Stay away from me, or I'll cut you." Chuck and Sarah follow Juan Diego to his room, and she makes it into the room but he doesn't, when the door is kicked closed on their handcuff chain. She fights with all of her other limbs and tells Chuck she's got it, as Chuck stands in the hall, telling people who pass by that he got locked out of his room. Sarah tosses Juan Diego into the bathroom and closes the door, then opens the other one. Chuck topples in on top of her, where they land on the bed in a very sexual-looking position, her feet in the air. And that's when Casey comes in. He's disgusted, because two spies should be able to come up with a better story. Chuck swears the terrorist's in the bathroom (how does he know that?!), and Casey does find him there. He shoots him with some tranq darts and says he believes them now.
Casey asks Chuck and Sarah for an explanation, but the tranq darts hit his little notebook of numbers and names, so he runs out of the room. Casey follows and sees Morgan's blocking the path of the terrorist. He tells him to get out of the way, but instead Morgan (accidentally) uses his giant backpack to knock the guy out, then praises himself. When they're out of the train, Morgan tells Juan Diego, "We're CIA, dirtbag!" Chuck tells him it's not the best idea to share that with just anyone. But it works out well in this case, because it gives Juan Diego the opportunity to tell them that it would be odd for CIA agents to take out the Interpol agents he'd turned himself in to, and that he was going to give up names of other leaders. Casey asks if this mission was run through General Redhead, but they wanted it to be on the down-low. Morgan doesn't get why, but Casey tells him they're quitting. Morgan's so not okay with this, because, Chuck's a spy! But they tell him they want to be together, so they're quitting after handing over Arnaldo. Casey gives them keys to take their cuffs off, and Morgan's faux-Canadian hottie gets off the train and makes a phone call. She tells whoever's on the other end that someone did their job for them by neutralizing the Interpol agents, but now she'll follow Arnaldo and his new friends and make sure they never talk. In shows like this, "never talk" usually means "death."
Chuck's on the phone with General Redhead (and not just any phone, but a red European phone booth), who's scolding him for taking Arnaldo into custody without contacting her first. She's sending more Interpol agents to get Arnaldo, and asks Chuck not to assault them. He tries to explain that they didn't assault those others; just knocked them out with pharmaceutical narcotics, but that's not helping. She tells him to keep Arnaldo safe until the Interpol agents get there, then get back to Burbank immediately, with a good explanation for ... But his phone runs out of money and he tells everyone they get to hang out here for a little longer, so it's like vacay.
Juan Diego's in the unluckiest seat ever, in a coffee shop, listening to Morgan whine to Chuck about how he can't believe he's just quitting. He can't even enjoy his so-delicious-it's-like-it's-straight-from-a-cow cappuccino. Morgan asks Chuck how he can leave without saying goodbye to Ellie, but Chuck says she's going away to do something she wants to do, and he's happy for her and Devin. At another table, Casey's giving Sarah the same lecture. He thinks she's throwing away her life for Chuck, but she says they're making a life, and they are not going back. Casey says he won't stop her, unless she wants him to, because he knows what it's like to make a choice like this. Both Chuck and Sarah say they choose each other over being a spy. Arnaldo speaks up and asks Chuck if it has to be a ch