Vincent is finally old enough to help his parents with their job at the zoo, along with his sister.
The thing is though, this is not a normal zoo.
Hidden away in Artis (a Dutch Zoo), behind the aquarium is the Ondierentuin*, the Monster Zoo that is guarded by a troll.
* I couldn't think of a proper translation in English for ondier. Dierentuin means zoo (literally animal garden) and dier means animal. Adding on- to dier makes it negative and the best I could translate it to is monster).
Vincent and Ingrid's parents are zookeepers in the Monster Zoo, along with other adults and their children.
They take care of loads of animals, such as dragons, a sourpuss, stone-eaters, whistling spiders, pink giraffes that depress everyone with their sad songs, a unicorn and giant ear owls, who can shrink and grow to whatever size their cage is.
But Vincent's favourite animal is a rabbit with super soft blue striped fur.
It's the only one that they know of.
Strangely enough the page about blue striped rabbits, also called moon derghs, has been torn in half from the Monster Keeper handbook, that was written by Vincent's ancestor.
After a while, animals start to go missing from their enclosures.
The kids decide to find out what happened.
Ingrid takes out Cordelia, the zoo's unicorn, to help find them as she's an excellent tracker and artist.
Cordelia discovers the missing animals' skeletons in their cages and draws a strange creature in the sand when Ingrid asks her who did it.
The animal has enormous teeth and claws, bat-like ears, spikes and legs made for jumping.
The children show the adults, but they have never seen or heard of such a creature.
They decide to keep an extra eye on the animals to ensure no more are harmed.
Later, another rabbit is brought in by Vincent's dad.
It's not long before the two rabbits breed; the female actually gives birth to super cute babies as the zookeepers discuss her newly discovered pregnancy.
Vincent is allowed to keep one of the babies as a pet and he takes it to school for his presentation.
A boy in his class, Heiko, is jealous; his father Berend owns a huge pet store with rare and exotic animals but doesn't own any blue striped rabbits.
He tries to trade Vincent's rabbit for one of his pets but Vincent will have none of it.
When he picks up his rabbit to go home he discovers it has been switched with an ordinary painted rabbit.
Late that night Ingrid helps him track down his rabbit, of course with help from Cordelia.
They discover it was indeed Heiko's dad who's got the blue striped rabbit.
When commercials start to appear on tv for blue striped rabbits the kids decide to tell the adult zookeepers.
A visit to Berend's store results into nothing despite bringing their land shark. Now there's so many rabbits they aren't rare anymore and they can't confiscate them.
Things go on for a few weeks. The rabbits become more and more popular throughout the country.
When Ingrid tries to muck out the rabbits' enclosure they find the missing page on blue striped rabbits, torn into a hundred pieces.
What they find is not so pleasant.
The cute and innocent looking rabbits turn into deadly moon derghs when the moon is full, armed with diamond claws and poisonous spikes.
Weapons bounce off from its spikes and it can dig through concrete to get to its prey.
Seeing as it is a full moon in three days, they decide to break into Berend's house and get the hundreds of thousands of rabbits back before the entire country is ripped to shreds.
With help from their troll and a giant ear owl they reach Berend's mansion.
Vincent and Heiko narrowly escape from Heiko's rabbit, who is briefly turned into a moon dergh and gets eaten by Hugeir the troll.
All together they device a plan; they get every rabbit owner to hand in their pet for a 'contest'.
They put all the cages together in the Amsterdam ArenA and cover it up with canvas, so the moonlight won't reach the animals and give them the power to transform.
Things go awry when the giant ear owl returns and rips the canvas.
Everyone takes cover in an emergency exit as thousands of moon derghs break out of their cages and start fighting.
Only in the morning, when the sun has risen, dare they venture out again.
The moon derghs have fought and eaten each other, with a few bloated individuals still strolling about.
Individuals, that would make a great snack for a giant ear owl....
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