Hammy spots an old boot floating down the river and decides it would make a wonderful place to live. GP uses his amazing new invention to help, and everybody pitches in to build a home for Hammy.
Hammy and Martha get lost in an early morning mist on the river, but GP and Turtle set out to rescue them in GP's balloon.
Hammy, Martha and GP set off on a birdwatching adventure and come to the aid of a squeaking Weathercock.
Martha builds a kite for the annual tug-of-war with the Wind. The contest begins, but Wind catches GP cheating.
Hammy and Frog offer to help Martha solve the mystery of her disappearing acorns.
Granny Rabbit borrows Martha's boat without permission to make a shelter for her grandchildren, and the whole Riverbank springs into action to help make Granny a new home.
Hammy finds an old map and goes off in search of buried treasure, but all he and GP find is a package of mysterious seeds.
GP finishes his flying machine and starts boasting that it's the fastest thing on the Riverbank. Turtle accepts his challenge to race, but when Turtle is injured and Wind agrees to run in his place, GP learns such a lesson that he resolves to never boast again.
Martha's nephews sneak in while she's asleep to borrow her father's pipe, some soap and a pail. Soon enough the woods are filled with lovely, squishy bubbles.
One day while fishing, Hammy thinks he sees a monster peering at him from behind some bushes. He and Martha go back to investigate.
Hammy decides to build a diving bell out of parts he finds in GP's garage.
Everybody joins in when Martha suggests GP host a garage sale to get rid of some old junk.
After a ferocious summer storm, Hammy and Martha find a Golden Coach in a clearing. After everyone takes turns going for a ride, Granny Rabbit suggests they all take it back to its rightful owner.
Hammy's dreams of flight are dashed when his goose-feather wings don't work, but GP and Martha team up to make his dream come true.
When out looking for new subjects to paint, Hammy finds a beautiful moose who he decides must be King of the Riverbank.
Hammy is excited to use his diving bell again when he and Martha find a sunken boat in the river.
After raising the old tugboat, Martha and Hammy repair and polish it. When Hammy takes the vessel out on the river, he hears a far-off song that leads him to a surprise.
GP invents a popcorn machine but forgets to turn it off before he delivers the mail, leading to the biggest popcorn flood Riverbank has ever seen.
The River is rising swiftly and Hammy goes upstream to investigate, but GP has another idea about what might be holding back the water.
Hammy meets a shy pygmy hedgehog named Hairbrush Henry who jumps at the chance to appear on GP's newest invention: television.
Wind has gone away and all the animals miss him, so they set off to find him in GP's balloon.
GP spies a mysterious white, dimpled object through his telescope. When it crash-lands on the Riverbank, the Wise Old Frog calms GP's fears and the animals hatch a plot to send the white ball back where it came from.
The mysterious Mr. Spooky arrives for Scaryday, scaring Hammy, Martha and Turtle and sending miniature spookies floating all over the Riverbank - all in good fun, of course.
Hammy gets restless when he sees all the animals preparing for winter, but Martha explains to him that some of the animals must hibernate until spring and GP eases his worries with an autumn drive.
The animals awake in the middle of winter to find the Riverbank buried in snow, and they are shocked when the snowman they build suddenly demands chocolate cookies.
A curious Hammy sets out to find where spring comes from, but he puts the search on hold when one of GP's favorite inventions goes missing.
The Wise Old Frog puts a twist on his storytelling session by having all the animals act out the story of Little Red Riding Hood, finishing with a scary surprise for Hammy.
When trying to deliver mail from his airplane, GP accidentally drops a package intended for Martha in the woods.
Martha thinks everyone has forgotten her birthday, but Hammy bakes a cake and throws a surprise party for her.
Wind brings a model sailboat down the river, but things don't go so well for Hammy when he climbs aboard.
Wise Old Frog is telling ghost stories one evening when a strange laughing creature swoops down from above to scare them. The next morning, Hammy and Martha meet this spooky stranger.
GP's nieces come downstream to sleep over at the Old Mill and cause quite a commotion.
Hammy decides to become a famous detective, so Martha makes him a special hat and lends him her magnifying glass. But what Hammy really needs is a mystery to solve.
GP has a cold and cries for sympathy, but after getting such nice special treatment from Hammy and Martha, he isn't eager to admit when he starts to feel better.
For once it's GP's turn to be rescued when he and Martha take off for a picnic in GP's balloon and get stranded on top of the Scary-High Cliff.
Hammy decides to make a toy boat out of a cork he finds floating downstream, and soon it becomes the most popular toy on the Riverbank.
Captain Toadie remembers how Hammy and the others rescued him and his tugboat, and returns the Riverbankers' kindness with a gift of band instruments.
Martha is missing the bobbin off of her sewing machine, and Hammy tries in vain to find it.
A mysterious, dinosaur-like creature appears fleetingly behind the bushes and scares Hammy and GP. Martha joins in to investigate this new stranger.
Hammy, Martha and GP take the Dig-a-ma-bob on an archeological dig at which they find an old comb, a stick and a toothbrush.
GP builds a unicycle out of a discarded bicycle wheel that Hammy finds in the woods, but when GP takes the cycle out for a spin he quickly loses control of the giant wheel.
The annual Riverbank Day is marked with the Riverbank Fair, which starts off with a parade and features a baking contest with Hammy as the judge.
Hammy dreams that he finds a long, silver spaceship that takes him and GP into outer space. When he wakes up, however, the story seems to start all over again.
GP gives Hammy a dusty old trunk from his attic, and Hammy discovers it's full of hats with magical powers.
Hammy starts a book of records for a restless GP to break. GP decides to break the diving record held by Turtle, with a twist - he'll be diving through the sky.
Wise Old Frog decides the Riverbank needs a general store, and Hammy just happens to meet the right animal for the job.
Hammy's cuckoo bird gets wanderlust and takes off to see the world, but now Hammy can't wake up properly.
A drought strikes the Riverbank, and Wise Old Frog suggests they do a Rain Dance.
GP builds a robot called 'BOROS' (Battery Operated Rodent of Steel) to do all his work for him so he can have more "thinking time," but BOROS ends up being a little too successful.
Timothy Tortoise brings his circus to town, and all the animals are excited to perform.
It's Christmas on the Riverbank and Hammy, Martha, GP and Turtle set out to find a tree and exchange gifts. But when a mysterious stranger steals their tree, the animals track it to a lonely cave deep in the woods and find a Christmas surprise.
GP helps Turtle build a 'Turtle-ma-bob' that can climb over almost everything. All goes well until Turtle decides to test out a special button on the machine, sending him on a wild ride.
After Wise Old Frog tells Hammy the Legend of the Lost Bells, he and GP team up to track the bell sounds deep beneath the river.
GP insists on giving Martha a better way to clean up the river, Hammy a better way to dig his garden and Turtle a better way to count his steps. But he just might be pushing himself too hard.
Turtle decides he likes living in his shell so much he wonders why everybody else doesn't do the same, so he heads off in search of fellow shell-dwellers.
Hairbrush Henry isn't shy anymore, and returns to dazzle everybody with his new motorbike singing act...until he crashes the bike into the river.
Martha builds a houseboat so she and Hammy can go cruising, but it's too small for GP to join in so he decides to build an invention to call them back home.
Hammy finds some eggs in the bushes and thinks they belong to Robin, and soon all the animals have come together to gather up all the eggs. But Granny Rabbit and Ferret both have surprises in store.
Martha and Wise Old Frog try to cheer Hammy up when he wishes he was bigger, but it's only when Turtle gets into a tight squeeze that Hammy realizes being small can make a big difference.
Uncle McTavity asks GP to build him a computer to play the bagpipes for him while he runs the general store.
Hammy is very puzzled by Cathy Caterpillar's transformation into a chrysalis, and GP is convinced that it's full of aliens from outer space.
Martha realizes teaching Hammy about time wasn't such a good idea when the nervous hamster begins to stress about fitting all his daily activities into twenty-four hours.
GP'S globetrotting Battery Operated Rodent of Steel (BOROS) returns home for a visit, and all the animals try to impress him by boasting about how exciting their lives have been since he has been away.
Martha builds a huge airplane so she can take her friends to see the world, but they only get as far as the barnyard before they run into some trouble.