OK, Alexa, I'll make a quick stab at it mostly from memory and also referring to the on-line script (I love those):
It starts off with a recap of Chairman Hwang's challenge: the company goes to whichever son can get him Hwaandang. (How come Yu-il, his daughter, can't play?) Chanmin and Donggyu see each other off in the night, with Donggyu wondering what chance he has against a player like Chanmin. Meanwhile Yu-il talks with Chairman Hwang and he tells her that basically he is still rooting for Donggyu, but he thinks he needs to be spurred on by a rival.
Meanwhile, Suha is still sitting outside the Seoul house talking with her brother, Joon-young, who repeats that if he were given Hwaandang he would just sell it. Then Jeong-sook turns up, starts going after Joon-young in her usual over-the-top cloying manner, and then whisks Suha off to a karaoke place, where they sing for a long time and Suha gets smashed. Her earlier line about how her constant round of ceremonies has given her a high tolerance for booze is completely bogus apparently. This is her second time getting soused in what, two days?
Next Joon-young is carrying Suha home on his back, with Jeong-sook tagging along going on about how handsome he is and how pretty she herself is. Jeong-sook gets the unconscious Suha into bed, looks around the place, and decides that she likes it and is going to move in! There's plenty of room in the bed, and Suha has nice clothes in her closet. And she is having problems paying her own rent.
Next it's morning, and poor Joon-young is in the bathroom in his T-shirt when Jeong-sook rousts him out to make more passes at him. "I thought I'd offer you a towel! .... It's my best teddy bear towel." Jeong-sook proceeds on to breakfast where she wolfs down everything in, sight under the disapproving gaze of the entire Li family, then unconsciously committing terrible gaffes by going on about how Suha's mom (really her stepmom of course) cooks so well in the old Hwaandang way, she must have learned from the long line of great manor ladies and so on, to the point that Suha has to break off her own meal and physically tear Jeong-sook away from the table and hustle her out. Once outside, she clues Jeong-sook (and the audience) in to the fact that her dad's current wife was a woman he took up with while studying in Seoul, being already married to Suha's mother, and that in fact he had two households at once for a while and that's why her half-brother is actually older than her.
Donggyu meets with his father and they talk about strategy in Sun Tzu-ish terms (to shoot the general, first you shoot his horse, then you tie up the general and lead him with a rope, etc etc), and then there is a fantasy sequence of a boxing match between Donggyu and Chanmin, and then we get back to Suha, who has been dragged off to a race track by Chanmin. She is suspicious of this - how can this be business, after all? - but then lo and behold a big Japanese buyer shows up with his entourage. Chanmin tells Suha he is a big racetrack gambler and she should help him out. With her one sentence of Japanese and a few fractured words of English mixed with Korean, of course she charms the guy, and then she starts picking out winning horses using god knows what mixture of numerology and mystic visions! A huge crowd of bettors is soon gathered around trying to get tips from her! If she can do this regularly, she can pay off all her loans and get enough to restore Hwandaang to its days of glory in short order, you would think. Anyway, the buyer cleans up and gives Suha an envelope with 5 million won in it (that's about $5K) which of course she immediately stuffs in a poor-box, as her grandfather told her that easily gained wealth should be used to help others.
Chanmin, however, then takes her out on a ferry cruise on the river - in fact, it turns out he has rented the whole boat. He hints that "this is what people do when they are going to propose" - a hint that Suha misses, of course. But the boat trip is cut short when Suha gets an incoherent phone call from granny down at Hwandaang, and of course she has to race right down there on the bus.
Because while all this was going on, Donggyu was putting his own strategic plan into action, which basically involves bribing his way into Hwaandong with presents and sweat equity. He and his driver have gone down there with armloads of gift bags, but gramps threw them out pretty quick. But that was just the opening gun. Now some delivery people have shown up with the heavy artillery and unloaded it: a massage armchair for gramps, and a karaoke machine for granny! I should mention that there is some kind of singing contest in the neighborhood, so granny and this other woman (I really haven't learned the names of the Hwaandang retainers yet, sorry) really can use a karaoke machine. When they first unloaded the stuff, granny was quite upset and that's when she called Suha, but by the time she gets there they are all quite seduced. By the way, it's awfully suspicious that there is this singing contest in the neighborhood just then, and that Donggyu knows they can use a karaoke machine. Anyway, Suha gets down to Hwaandang (crossing paths with Seo Hwaran, who is skulking around planning to destroy Hwaandang and turn it into a theme park) and finds HDG busy ingratiating himself by washing the dishes. Unfortunately HDG starts talking about the stages of his plan to his assistant while Suha comes up behind him to listen. Suha of course wants all the loot taken away, but Gramps and Flower's mom really don't want to give up the massage armchair, and in the scuffle over it the chair ends up getting dropped on Donggyu's foot (start counting up his Hwaandang-related injuries, this makes two).
Granny persuades Suha to at least let him stay for dinner. Gramps goes out to try to kill a chicken, but they are all pretty agile. Donggyu offers to help and he and his driver chase chickens around to no effect for a while. Then they find a strange-looking chicken (it didn't look that strange to me, but what do I know? and they were right, as you will see) sitting on a pot. Suha says it's a "lacquer chicken". Donggyu decides to whack it with a stick. He hits the chicken but also breaks the pot, which contained - this is just about the funniest sequence in the series so far, IMHO - Suha's great-grandma's 80-year-old SOY SAUCE! She breaks down in tears over it. They all try to salvage as much of it as they can from the pieces of the pot. Donggyu can't believe the fuss: "It looks black and sticky. Are you sure it's not rotten?" Suha then goes off on him about the soy sauce for a long time. "How can soy sauce go rotten? You don't know what this means to me! There was a whole cow hip in there! There were abalone and (some flower and some other thing). This was the soy sauce that a great chef begged on his knees to have! When people get sick they ask for this soy sauce. It's a great medicine and a great treasure! You should be more careful around other people's houses!!"
Things are not going well for Donggyu, but at least he can help cook the chicken, right? He sneaks a look in the pot to see how it's doing, a cloud of vapor hits him in the face, and -
Next scene - the local clinic! Donggyu is getting a hypo in the butt. His face is all covered with awful hives! (Three! What do you want to bet the final count will be?) The doctor explains that one in a hundred people have awful allergies to lacquer chicken. I bet you didn't know THAT, did you? Why do they even raise the things? Actually, the doctor goes on to mention that some men believe that eating lacquer chicken gives them "stamina". (Yeah.) At this point Suha and Donggyu start squabbling, with Suha accusing Donggyu of wanting to eat lacquer chicken for crude reasons, and Donggyu saying that she was the crude one, pawing at him as she did during the island business, and Suha lets it slip that by now she really does remember what really happened, even though she won't admit it. The whole thing convinces the doctor that they're an item - (Both: "We're not together!" Doctor: "Oh I see .... well, your husband is going to be very itchy all over for a while.." Both: "We're not married!!!")
Donggyu spends the night at Hwaandang, and Suha actually starts to feel sorry for him, fanning his face, as he talks about how his mother would fan his face when he had the chicken pox and apologizing for the soy sauce and everything else.
The next day she rides back to Seoul with Donggyu talking with each other very openly about their families (you can see, by the way, that getting the hives may have been the best strategy of all) and she explains more about her history. The elders wanted her father to marry early, and he married a local woman and then went off to Seoul for his studies. But when it came out about the other woman (now his wife), the elders disinherited him and bestowed Hwaandang on Suha. But her mother never had a harsh word for her dad, for all that he was cheating on her. And she tells about the dumplings that her mother used to make for her dad and how they were his favorite food. After he lets her out, Dong-gyu says, revealingly, "Why are my heart pounding and my face burning?" "Probably the itching," says his driver. Yeah,
riiiight. You're hooked but good, you poor sap
So when she gets back to the house in Seoul (where, by the way, Jeong-sook is still squatting, and is now raiding Suha's closets, trying to convince herself that "We're exactly the same size" even though some parts don't quite fasten), and finds her mom and Joon-hui out, she decides to whip up a batch of kimchi dumplings for her dad. At this point there is a hilarious cooking-show type sequence with Suha and Jeong-sook, where Suha, breaking frame, presents to the audience her recipe for dumplings where you start with kimchi and "imagine it is the man you hate worst of anybody in the world, and you get your knife and CHOP CHOP CHOP HIM TO DEATH. Then you get some onions and [other ingredients] and CHOP CHOP CHOP THEM TO DEATH. Then you fold it up in the dough very tightly because if you leave an open space he might get out and you will have to see his horrid disgusting face. Then you boil him to death!!" I'm not attempting to do the whole thing verbatim, and I'm not doing it justice. It's really funny. Sorry you missed it!
So, the dad really loves the dumplings. Meanwhile the stepmom and Joon-hui are coming back from the shopping, and they find that the dad has already eaten, and the stepmom, who perhaps knows the meaning of the dumplings, is harsh and cold about it - "he shouldn't eat anything with flour in it" - and Joon-hui is nasty too, and the stepmom takes the remaining dumplings and throws them in the garbage, and Suha loses it and starts crying, because of how the dumplings symbolize to her the loving times she had with her own mom when she was alive and her dad when they were all together, and she fishes them OUT of the garbage and runs out of the house with them into the night and trips and spills them and scrapes her leg and sits there crying, and just at this time she gets a phone call and it is Dong-gyu, who is in the neighborhood returning something she left in the car. But she is upset and incoherent, and Dong-gyu, who is of course terribly in love with her by now, asks where she is. "By a playground", she says. (Is Tae-young hanging around there still? :-) ) He rings off, and then a car shows up, but it is Chan-Min, who has come over on general principles and finds her crying and upset. He sits with her and comforts her and puts his arm around her, and just at this moment of course Donggyu shows up and slugs Chan-Min, and Chan-Min slugs him back, and it's the end of the episode!