The morning of 1 April at the Roosen home. Lucas (12) would prefer to stay under his duvet all day. In the afternoon, he is due to perform with his secret crush Charly (12) at a youth music audition. He has terrible stage fright. Then an ingenious April Fool's joke by father Lutz shakes the house. It was actually supposed to be a hidden declaration of love to his wife Maria, but she is less than amused. Guest student Xi Zhōu (12), on the other hand, is all the more amused.

A short time later, the young Asian rehearses his first prank on Schaaf (21), the boyfriend of Lucas' older sister Caro (19).The wannabe rapper has hired himself out as a pizza delivery boy at a dubious takeaway.Xi Zhōu puts his pants in a pizza box and swaps it for one from Schaaf's delivery.What he realises too late: the captured pizza box is filled to the top with neatly bundled banknotes!Apparently Schaaf was supposed to deliver a disguised protection money delivery.Lucas is beside himself.He already finds the sheer presence of the cheerful Chinese man an imposition, and now this! Not that he particularly likes Schaaf, but he doesn't want to be responsible for his death due to a missed delivery.

In their distress, the dissimilar boys make a pact and try to save Schaaf. With Caro's involuntary help, they actually manage to get the pizza box back to Schaaf after considerable hardship.

For a moment, everything seems fine and our heroes celebrate their successful adventure. But this day is different: Schaaf has an accident and sets off a chain reaction of new events. Now Lucas and Xi Zhōu have a real problem. The two of them are caught up in a whirlwind of events that not only puts the tender bonds of their budding friendship to the test, but also involves Lucas' whole family. Only one thing is certain: nothing is as it seems at first glance. Schaaf's clients from the takeaway turn out to be harmless, but real gangsters are called onto the scene who want to know who is poaching on their turf. And to add to the chaos, two policemen who have been suspended for incompetence are hot on their heels. Luckily, Charly comes to the boys' rescue and the odd couple become a brilliant trio!

After numerous surprising twists and turns and further levels of escalation, it is ultimately up to Charly, Lucas and Xi Zhōu to recapture the spirits they called. In the eye of the greatest possible disaster, they realise that only another April Fool's joke will save them all...