We open on a peaceful, sleeping little house. Suddenly, there's a loud noise! Some kind of prowler/possible prairie ripper is creeping outside! Pa runs outside shooting, only to be met by William O'Hara, a self-proclaimed circus man who was trying to be a good neighbour by saving the little house from bobcats.
Neighbour? O'Hara, we know you're not from around here, so save the bullshiitake for someone who... oh, nevermind, Pa has invited him to stay. I guess my suspicions against this guy were totally unfounded. His bizarre wardrobe and crazy eyes make him a natural choice for someone you'd want to have around your family.
The next morning, O'Hara stops Mary & Laura when they leave for school. Actually, he pops out from behind a clothesline he put up. He's got a talking bird, and an exotic congrilla, "masterrrrrrrr of the jungle!" Except it's freaking Bubbles. It's a chimp, you guys. Mary's got a good head on her - she's not buying this guy's fantastical stories. She's totally scornful. The girls leave for school, and O'Hara impresses Ma & Pa with some fancy sleight of hand tricks over at the chicken coop. Old guys: annoying people with lame tricks since 1872!
Later, at the mill, Hansen is complaining about a headache. Doc Baker thinks it's time for a check up. Hansen can't go for that, no can do. He's been taking pills and they don't work! He doesn't trust the doc's modern medicine. Uh oh, I smell a mystical circus man cure... or else Hansen's gonna get turned into a congrilla.
Back at the little house, O'Hara brings the drama, yelling: "Thief! Robber!" out loud into the darkness of night. Pa goes to investigate & finds no Plum Creek Strangler or anything, just O'Hara on the ground. The prowler "crrrrrrracked a couple of me rrrrrrrrrrrrribs".
Pa tapes up O'Hara's ribs inside, then for some reason sends Mary out in the dark to the crime scene to get some stuff from O'Hara's wagon. O'Hara starts brainwashing the children with his extreme accent hypnosis. He mixes a potion that's gonnna heal his phony broken ribs with one delicious sip.
The next day, Hansen's at the Merc. These pills are not helping his headache! Is there a money back guarantee by any chance? Apparently the medicine is good for a whole whack of old fashioned ailments (I'm talking coated tongue, thin blood, and spots before the eyes), but not headaches. Lucky for Hansen, Mary & Laura are in the mercantile too, and start telling him about O'Hara's secret medicine elixir. He boots it to the congrilla wagon. Just seconds after using the potion, Hansen is cured.
Doc Baker is furious that Hansen won't submit to a full examination. Doc even tells off Charles about the situation. He cares so much about Hansen... it's a little weird. Plus, Doc's got O'Hara's number: he cured Hansen for free, this time. Next time, woo woo, Daddy needs a new pair of shoes. Pay. Up. Sucka.
O'Hara has the stinkin' guts to go into the mercantile. Doesn't he know that his bogus remedy is taking business away from honest merchants? OMG, are you serious, Harriet? I might side with you on this one, but you torture Ma about the eggs EVERY SINGLE DAY. That's kinda sleazy.
Harriet informs this circus drifter that his time in Walnut Grove is up - they don't care for scalliwags here. O'Hara picks up a fricking anvil offa the floor, presumably to bash Mrs. O... nope, just showing off. His imaginary ribs are broken, but look what he can do. No sham medication could give you that result!
Turns out Mrs. Oleson has some private pain that even Doc Baker can't fix. Why'm I saying "even"? Pretty much nothing gets cured on his watch. He watches ladies give birth & stalks Hansen... annnn' thassit. O'Hara agrees to give Mrs. Oleson some medicine to try, free of charge.
Doc Baker rides into Plum Creek like a bat outta hell. "A useless remedy is as dangerous as a loaded gun!" Appropriately, Pa tells him to calm the shit down. Harriet Oleson has a serious case of appendicitis, but won't have surgery because O'Hara's elixir is gonna fix her.
Ma & Pa start to have second thoughts about hosting old Willy con Carny on their land.
Doc Baker strong-arms O'Hara into convincing Harriet to get the operation. He visits Harriet on her soon-to-be-death bed, and tells her that only royalty get this type of surgery, so she should totally go for it. I heart manipulation. He does this really creepy wave on his way out the door. I thought he was bad with his hat ON. Ugh.
So, Doc does the surgery. The entire township is gathered on the mercantile's porch, I guess to see if Harriet makes it. I can't imagine that they all care. There's probably just nothing better to do. Doc comes out looking totally haggard.
Time's REALLY up for O'Hara. He admits to Pa that the powder is blarney. Now he's gotta slink out of town under the cover of darkness.
The next morning, Mary & Laura are disappointed to find him gone. It's the freakin' weekend & they wanted to learn some magic tricks! Well, get hip to the fact that the number one thing you gotta know about circus people is that they're unpredictable. Pa buys the girls' happiness with pennies for candy.
Laura & Jack chill in front of the merc until a kitty agitates Jack.
He runs in front of a wagon & is dramatically run over right before a commercial break!
Laura freaks. O'Hara's the only one who can fix Jack! Pa tries to break it to her that O'Hara was a big faker, but she won't believe it. Pa thinks maybe the kids could use a hard lesson & goes to find O'Hara.
They arrive back at the little house after dark. O'Hara gives Jack the potion. Pa wants him to come clean to Laura, but O'Hara wants to keep hope alive until Jack either dies or lives permanently.
As the night goes on, Jack eventually stirs awake. Laura believed! If O'Hara stayed in Walnut Grove, there'd be no sick people or animals! They don't even need a doctor. Baker's been rendered obsolete! Pa gives O'Hara a major stink eye while Laura spouts off. He finally tells the g.d. truth that nothing about him is real, not even his name or the way he talks. Oh, great. I've been sitting through this accent for 43 minutes & it was completely unnecessary?! Boo!!!!
O'Hara finally leaves in what shoulda been disgrace, but Pa invites him to come back sometime. Spoiler: doesn't happen. All together now: "And he was never seen again!"