This episode starts out with Henry Talbot and his pal, Charlie Rogers, racing, so let's trot out some car metaphors, shall we?
If we had to assign a theme to tonight's show, it'd be "hitting the brakes." Violet, for instance, is quick to derail the plans of Lord Merton's future daughter-in-law, Miss Cruikshank. Suspicious as to why Isobel would be invited to Miss Cruikshank's wedding all of a sudden, Violet pays the bride-to-be a visit. Cruikshank may be a tough nut, but Violet's a "tough nutcracker," you see. Soon, it emerges that the "cool little miss" and her husband are hoping to reunite Isobel and Lord Merton so they don't have to deal with him as he ages.
Violet warns Isobel just before she sets sail for the south of France. She's hoping a holiday will help thaw her rage at Cora and entice her to come home. As she notes, a month among the French should do the trick.
Mrs. Hughes, meanwhile, is hoping to put the brakes on Carson's domestic demands. With the help of Mrs. Patmore, she's able to fake an injury like she's an Argentinian soccer player. Carson gets a taste of his own medicine when he's forced to make dinner and wash up. Patmore, however, has other business to attend to. Her new bed and breakfast is up and running, but a strange man seems to be watching the house. Dun dun dun.
Henry gets a green light when the Crawleys (and Bertie!) accept his invitation to watch him race at Brooklands. When he drops in unannounced at dinner in London, Henry tells Mary he's taking it all as a good sign. Not everyone's convinced, though. Cora has doubts about whether or not the race car driver will make Mary happy. Even Anna suspects their lives "may not fit."
Tom, however, is Team Talbot all the way, mostly because it means he gets to watch lots of racing. The family, accompanied by Edith's lady editor (seriously, that's what they call her), head to Brooklands and marvel at everything. Imagine them at Nascar.
On the track, Henry and his bud, Charlie, are neck-and-neck, egging each other on. Mary's about to pass out from overexcitement when there's a crash. Poor Charlie has gone off the track and died in the resulting crash. Henry is devastated, Mary tries not to make it too obvious that she's glad he didn't die, and much is left unsaid.
Until dinnertime. After dinner, Henry calls Mary up and, in the spirit of "carpe diem," forces the issue of a future with her. She breaks it off, telling him the racing thing is too much for her to handle and she could never force him to quit. Tom overhears and voices his disapproval of her decision. Is he a Mary and Talbot shipper, or does he just want more racing tickets?
While the family is away, Daisy and Molesley take a break from their exams with a little picnic. It's all fun and games until Daisy tries to make the illiterate Andy read her exam question. Thomas tries to cover for him, but the secret is out. The good news for Andy is that the local teacher offers to teach him. The bad news for Thomas? He's lost the one bit of social life he had.
Despite the somber outcome of the race, there are things to celebrate. For one, Bertie proposes to Edith. She asks to bring along Marigold, but fails to mention that her ward is actually her daughter. Secondly, Molesley does so well on his exams that he's offered a teaching job. He cries, we cry. And finally, Mama has sent her son a peace offering: a new puppy to replace his beloved Isis. Lord Crawley decides to name the pup Tio and reminds everyone about his love of Egyptian mythology.