Arnold and Gerald decide to take the bus a bit too far and miss the play that they are characters in, since Helga is in charge of it. Later, when Eugene's bicycle is ruined thanks to Arnold, he decides to take him out for a day of fun.
With fourteen beautiful inches of powdery snow, a blizzard has transformed Arnold's city into a winter play-land. But with the list of chores Grandpa has handed him, it could be July before he gets to play in it.
Arnold's best laid plans for the "ultimate Saturday" go up in smoke when he tries to complete all of his favorite things to do in one afternoon. On a boring summer night Grandpa tries to liven things up by telling a story about haunted Train Number 25.
The boarders are all suspicious of the mysterious Mr. Smith who lives behind door 16. Oscar Kokoshka moves in with Arnold when his wife, Susie, throws him out of their apartment following another fight.
When Arnold receives Mr. Hyunh's name in the boarding house's annual Secret Santa draw, he decides to make it the most special Christmas ever for the lonely boarder, and tries to reunite Mr. Hyunh with his long-lost daughter. Meanwhile, Helga agonizes over what would make the perfect present for Arnold.
Arnold is given the assignment to tutor Torvald, the meanest, toughest kid in Arnold's math class, for the big math test on Friday. Gerald convinces Arnold to allow him to spend the night at Arnold's house.
The first episode is "Spelling Bee", It's time to crown the spelling champ of the whole city, and P.S. 118 has two contenders for the $500 prize. In one corner, Arnold. In the other, Helga. The second "Pigeon Man", Arnold's prized pigeon takes ill, and only one person can help-the creepy recluse Pigeon Man. But when Arnold visits him in his rooftop roost he find they're birds of a feather.
When Helga's older sister, Olga, comes home from college and gets all of her parents' attention, Helga plots to sabotage her sister's visit. Arnold and Gerald save up cereal box tops to get a telescope before the arrival of Salley's Comet.
Arnold's pet pig, Abner, escapes one night while Arnold is sleeping. When Arnold tries to bring Grandpa's pocket watch home from the repair shop, he accidentally drops it down a hole in the street, which leads him to strange subterranean world.
Arnold gives an amateur magic show behind the boarding house and, for his big number, makes Helga actually disappear. When Arnold accidentally beans Harold in a baseball game, the bully vows to "kill" him, and gives him 24 hours to live.