Nobody believes 'snake boy' Paul Baumann reporting he spotted the first wolf in Waldau since over a century. Jonas changes his tune after finding a fatally bitten sheep in the same Black Forest section, adults divide in believers and mockers, but doc Hansen concludes it's true. Hunters set out, parents worry for their hiking children. A mystery man gets hold of the wolf.

As mayor Vinzenz Grieshaber's farm isn't earning enough, his wife Josefine advertised a room with board. City-dweller Schünzel arrives from Düsseldorf with his spoiled wife Marion, who abhors rustic food, and gaming-addicted teen son Quirin-Emanuel. Jonas is supposed to show him around o the farm, but abhorred to find his guest a sadist to animals, like new-born the steer-calf. Desperate about collect bills with the vet's local scrooge clients, Annette Hansen secretly caters for the tourists, but falls into a trip Jonas had set for Quirin, who finds her but is all but...

While the girl riding students bicker endlessly before and during their test at the Götz stud farm, a favorite horse gets a dangerous colic. Jonas is brought in to search for toxic food, but devoted stable-hand Bertus eagerly and ably assists vet Philip Hansen diagnosing the psychosomatic truth, an overdue lesson for the bitching brats.

When young stable-hand Bertus brings in his ferret for veterinary help and ably assists, Dr. Hansen makes him an eagerly accepted offer to become his trainee assistant, lessening his wife's workload so she can install a workshop for her minor restorations job in the barn. Jonas's gang hears of missing cats and dogs and sets chase to suspects textile hamper vans, including the year-back cool skater Timo, but arriving at the firm need help from Bertus to get in, and from doc to clear up what really happens.

Timo makes fun of Paul who presents in class his pet, a green snake from his late father. Later he brings it to the surgery, where doc Hansen is horrified to find it's not a harmless python lookalike of the green mamba as he thought, but the lethal real thing. When unsuspecting Jonas arrives with dog Oswald, the box falls and the venom escapes, causing panic throughout the village. Before it's caught, the Hansen dog gets bitten.

Jonas can just deal with the inconvenience and insecurity when the household and farm must do with him and father Vinzent, after his mother 'moves back to her parents' indefinitely after grandma made a fall, but unsolicited female 'sympathy' and speculations about a wrecked marriage are too much. Meanwhile Greta neglects school worrying about a goose that couldn't keep up with the migrating flock, which doc diagnoses just gastroenteritis, and marvels with Jonas at a gander who drops by searching for its mate for life.

Dr. Hansen is very pleased with his animals-devoted orphan assistant Bertie Heckenbichler, who even volunteers to help out as scooter driver when doc's car breaks down, but puzzled about his erratic behavior and utter mess I the surgery I the morning. He ignores it's because of Bertie's smuggled-in pet, a tame ferret. Since they had to leave the stud farm, Fred can't chase rodents there and bites things, like car motor belts. It escapes and gets sneakily taken in by the girls, but ends up killing a pet bunny. Doc has mixed feelings about flirtatious antiques hunter ...

Ex-con local adolescent Micha Moser trained his demented grandma's rottweiler for dog fights and terrorizes the school kids. Beig his age, Bertie is pressed by the kids to trap him into revealing the secret location of the illegal arena by pretending he trained the Hansen dog pretzel, a cute pooch, and wants to fight with him. Grumpy farmer Bischek, the vet practice's worst debtor, would rather delay therapy then pay up, but seeing Annette restores an old cuckoo clock, offers another deal: paying in antique kind, unaware his clock was his father's secret hiding lace ...

Veterinarian Dr. Philip Hansen learns from the desperation of the local beekeeper when one bee stung his naughty daughter. The real worry is to diagnose and hopefully cure the hive, as the children are taught how useful, even needed, the champion pollinators are for both wildlife and agriculture.

After initial disbelief of a teen sighting a wild boar in Waldau forest, panic spreads when it's confirmed and it even wounds the leg of Viktor Stelzl, the gentleman cavalier of grandma Almut. She's motivated to meddle even worse in the family of her daughter Annette and even Dr. Hansen's practice, but that doesn't stop Greta sneaking out to 'save the poor wildlife' which is the official target of mayor Vinzenz Grieshaber and forester Karl Nachtweyh's hunting parties, including the boys.

Waldau charmed by peddler Famula but divided about his naughty monkey, who is mainly kept in a tiny cage. While kids campaign to see the animal liberated, it becomes clear the recent wave of thefts may not be the work of poor orphan Bertie, whom doc suspects after finding missing cash in his lab coat, but rather fits the movements of Famula. Yet when they track him down to a ruin camp, his motives and attitude prove less then criminal.

It's hard to take serious the sighting of something resembling the forest devil' from local legend, which masks are modeled after, as worn for fun by Jonas. His Turkish classmate Cem is only interested in Greta's visiting Hamburg buddy, fashionista Chiara Eckhoff. But when the Hansen pet dog Prtezel gets missing, the girls go look for him and think the sight the devil near an old mine shaft he fell down, getting in trouble themselves. The men and boys must search and rescue them.

Shortly before Halloween, Waldau's leading contractor Alois Brackmann hires Annette to remodel the semi-ruin known to kids as the ghost house after his crew demolish half. But kids entering it on a dare are scared by 'vampires', rendered credible by a bloodily wounded horse in the stud farm. With Doc's help, it's established the house is inhabited by bats, a protected species, but not vampires, the horse blood has a more prosaic cause.