It's springtime on Borough farm and there are new-born lambs every where. On the cliffs Wendy the sheep has forgotten where she has left her lamb, in fact she's forgotten that she had a lamb at all! As Jake bounds off in search of the youngster, Mist faces the tricky task of reminding Wendy of the lamb that she is missing.
Deep in the heart of Borough woods lives a legendary sheep so wild that not even the great Sir Gregory could bring her back to the flock. But the Boss has decided that it is time for the Legend to be bought back into the fold, and one by one the dogs set off in search of her. It is only Mist who finds the Legend, living in a strange castle deep in the woods. As the Legend tells Mist of her quiet and contented life, Mist realizes that she must choose between the glory of returning with the errant sheep, or doing the right thing and letting her be.
Jake loves to roll, but when he rolls off a cliff and ends up on the sea shore below, he finds himself in a pickle, as even with his long legs he can't get back up again. Luckily for Jake a friendly Swedish seal called 'Sven' bobs up to lend a flipper. He kindly guides Jake back up the cliff much to the surprise of the worried Boss and Mist.
Sheep do some silly things, but getting stuck on their backs is about the silliest. When Vanessa the ewe becomes stuck belly-up while trying to rub an itch, Mist knows that she must act fast. As a flock of cackling crows circle around, Mist races to fetch help. Having woken the Boss they arrive just in time to put Vanessa safely back on her own four hooves again.
The Boss is so pleased with Mist that he decides to enter her in a local sheepdog trial. But as the crowd look on, Mist's boundless enthusiasm turns against her, as she rounds up a huge flock of the wrong sheep in the wrong field! The Boss is humiliated and Mist hangs her head in shame. Just as she thinks that the whole day has been a complete disaster Mist spots two faces that make her spirits rise. Could the two watching dogs really be her long lost siblings?
It hasn't rained at Borough farm all summer and life is dusty and dry. The dogs are hot, the fields are bare but worst of all the ducks' pond doesn't have a drop of water. Mist is keen to lend them a paw. However, guiding four ducks to a new pond is not as easy as Mist might have thought. She soon discovers that Steve, Jessica and co. never learned to fly, but undeterred they set off to waddle on a great journey that takes them back to exactly where they started!
When Fern overhears a whisper that she isn't pulling her weight at Borough farm, she is crest fallen. However, when Beatty the ewe gets stuck in the pond, with her fleece waterlogged, it soon becomes obvious that it is going to take a special sort of dog to save her. Right on cue Fern the swimming sheepdog wades into action.
Swift is not only the oldest sheepdog at Borough farm, she's also the proudest. So when she's overlooked for the tough job of bringing home the rams, she sets out to prove that she's still up to such a challenge. However, the rams, led by the fearsome MacPhereson, have different ideas, and it takes the timely arrival of Swift's son Ernie to save the day.
Mist's second sheepdog trial is far trickier that the first. She doesn't just have to pen the sheep, she has to find them in the first place. When she discovers that the sheep in question are the stubborn and downright dangerous MacPhereson sisters, she understands why all of the other dogs have refused to even try. Mist uses every trick to move the cantankerous quartet of sheep through countless obstacles and finally into the pen. Everyone cheers and Mist soaks up her moment of glory.
A dark monster lurks around the valley and panic is spreading amongst the Borough farm ewes. Mist and Jake investigate, and with the aid of Helen the Horse and Sven the Seal, hatch a plan to save the flock. As dusk settles a thousand sheep fill the valley, determined to prove that there is no place for a Beast at Borough farm.
If there's one thing that ducks don't take to, it's a tree falling into their pond. So when the worst happens Steve and his lady ducks waddle to Mist's yard in search of help. But when they arrive they find that the dogs have a problem of their own; a flood! While the lady ducks make use of the dogs' new pond, Steve wanders into the dog kennel from where he has some surprising news. "I've laid an egg and I'm not coming out until it's hatched". Leaving Mist with a problem to solve.
A heavy fall of winter snow is enough to test even the hardiest of animals. So when MacPhereson the ram wanders miserably away from the other rams, his chances don't look good. Mist sets out on a mission to find the old ram, and after a bizarre meeting with a herd of singing ponies, she finds MacPhereson and persuades him that MacVicar, MacCrae and the others still need his company.
The winter's work has taken its toll on the Borough farm dogs. Swift announces her retirement, Gail is feeling stiff in her joints and Ernie is suffering with an injury. With the lambing season just around the corner it looks as if the pack are going to be short pawed. To everyone's surprise Jake introduces his three month old son, Eddie, whom he tells them will be a fine addition to the pack. Everyone is delighted apart from Mist, who wonders how life will change now that she is no longer the puppy in the pack of the Borough farm sheepdogs.