Conni's cat Mau follows her on her kindergarten trip, causing mayhem, confusion and laughs. The children are kept busy hiding Mau from the teachers, tracking down a thief and saving a raccoon in an ancient castle's mill.
For the very first time, Conni goes on a big trip without her family. Of course her best friends Anna and Simon are joining, but unfortunately she is not allowed to take Cat Mau with her. As they arrived in the hostel, an old mill close to a castle, Conni discovers that Mau had come as a blind passenger. Secretly she cheers, although she knows that animals are forbidden in the castle and the hostess, Ms. Weingartner, is allergic to cats. Conni tries to hide Mau, but the cheeky cat cares little. He explores the surroundings curiously and does a lot of nonsense. Ms. Weingartner identifies her son's pet, the sweet raccoon Oskar, as the culprit and wants to take him to the zoo. And then things disappear from the hostel in a strange way. Conni and her friends have to act quickly: Will the children be able to save raccoon Oskar, tame Mau and also find a real thief?—youngfilms
For the very first time, CONNI is going on a big trip without her family, a trip with the other 'big' children from kindergarten, and boy, is she looking forward to it! The teacher HANNE and trainee LENNART will have their hands full with this boisterous gang.
An excited Conni packs her bags as if she were going on a month's vacation, with CAT MAU getting in the way, as usual. Conni's planning to take him with her. Everyone is allowed to bring a cuddly toy and Mau is her cuddly toy. Too bad Mom and Dad disagree. Mau stays at home! Conni's attempt to smuggle the cat in her backpack backfires, so she has to leave her little friend behind. But Mau has other plans!Finally, the class is on the way to the hostel, an old mill belonging to an ancient castle, which was built by BARON KUNO long ago. Sad Conni misses Mau so much she thinks she can hear him somewhere on the coach, but that's impossible...isn't it? Luckily, Conni has friends to cheer her up. And the best thing is that their new trainee Lennart turns out to be unintentionally funny. When SIMON and LARS fool around, playing the ghost of Baron Kuno, Lennart shrieks in fear - he appears to still believe in ghosts!
When the group arrives at the hostel, Conni's sad mood has completely disappeared. After dinner around a cozy campfire, everybody goes to bed. And guess who turns up to sleep on Conni's bed? Yes, it's Mau! The naughty cat had sneaked aboard the coach and hidden in the luggage hold! Conni's delight is quickly replaced with worry - animals are forbidden in the hostel and the hostess MRS WEINGARTNER is allergic to cats. If any adult discovers Mau, Conni will be in big trouble, and both she and Mau would be sent back home. Oh, Mau! What have you got Conni into now?! Conni has got to keep him hidden!
But playful Mau has other ideas! Early morning finds Mau outside, fooling around, only to land on a basket of eggs which fly into the air and land all around him! Unfortunately, Mrs. Weingartner blames the sweet RACCOON OSKAR belonging to her son LUCA. Conni feels awful - she knows it was Mau's fault, and she's responsible for him. At least for breaking the eggs. But not for the other weird things going on at the hostel. Things keep disappearing, and Mrs. Weingartner thinks Oskar is the culprit!
When Mau goes missing, a desperate Conni confides in her best friends ANNA and SIMON, who help search for him. But they only find a sad Luca. His mom is threatening to send Oskar away! To cheer him up, Conni tells him that she knows Oskar is innocent...but she can't bring herself to admit who really broke the eggs.
Since Oskar's troubles only starting happening with the arrival of Conni and her friends, Luca plays a mean trick on them during their trip to a former bear's cave. Using the shadow of his teddy bear, he pretends there's a real bear in the cave. Everyone is terrified, especially poor Lennart! His frightened screams echo around the cave!
Back at the hostel, Mau causes more mayhem and confusion! An annoyed Mrs. Weingartner phones the zoo to come and fetch Oskar! When Conni hears this, she bravely confesses that Mau is behind all the trouble, but Mrs. Weingartner doesn't believe her! In the evening, the hostess accidentally locks Mau in the pantry. Conni has to rescue him!
As soon as everyone is asleep, Conni, Anna and Simon sneak downstairs, but Luca hears them and silently follows. Mrs. Weingartner and Lennart are still downstairs, and the kids have to sneak past them, very quietly! They free Mau, who is quite disappointed - he's been eating all the cake!
Mrs. Weingartner and Lennart hear strange noises. Lennart fears, it could be Baron Kuno's ghost? Conni and friends hide in a room full of strange costumes and ancient armors. Luca, in hiding, frightens the friends, their screams alerting the adults! Fortunately, Mau manages to cause more mayhem, allowing the friends to escape back to the attic, but without Mau!
Luca now knows who is responsible for all the chaos! He confronts Conni, who sheepishly admits the truth. But since neither Mau or Oskar are to blame for the thefts, who is?! If they can't discover the thief quickly, Oskar will be sent to the zoo. The animal keeper is coming early next day! Joining forces, Conni and Luca devise a trap with modeling clay and a shiny toy. But will it work?
Indeed, next morning the bait has gone. Luca sees Mau and thinks it's him. Now he's really angry with Conni! When Luca is confronted by mom, who found his shoes in the costume room, Conni admits her own involvement. Ordered to stay at the hostel, she watches sadly as her friends leave for an exciting castle tour.
Suddenly, Conni discovers the trap! And the bird's footprints on the modeling clay! A feather brings her and Luca to the conclusion that a magpie has been responsible for stealing all the glittering objects. That's what Mau has been trying to tell them! With Mau's help, Conni and Luca discover the magpie's nest. Unfortunately, it's situated at the top of the castle tower, where MR POLDA is telling the other kids stories of Baron Kuno and his castle.
Conni's new friend Luca has a plan. It's a race against time, because the animal keeper will pick up Oskar any moment! They must prove Oskar is innocent! At the castle, a dressed-up Luca distracts the group playing Baron Kuno's ghost, while Conni searches for the stolen treasures. Luca tries to scare them away, but not even Lennart seems really terrified by this small knight! When the kids see Baron Kuno wearing sneakers, they chase after him. Will Conni be able to save raccoon Oskar, tame Mau and also find the thief?
