Michael O'Hara the Fourth(1972)

When her best friend's father is falsely accused of stealing the town's prized jingle bells, a young amateur sleuth and her friends must find the real thief before Christmas.

Max can hardly believe his luck: In a retirement home, he has finally found a gang that will let him join! Admittedly, it's the oldest and most wrinkly gang in the world - but that doesn't matter. He's found the best friends a 10-year-old could wish for in the elderly Vera, Horst and Kilian. Especially when, like Max, you're bullied in your new class and need help. But the gang's attempt to improve his school situation backfires. Horst, a former Bundesliga soccer coach, challenges Max's over-ambitious gym teacher Stöhle to a soccer duel: the school team including Laura and Ole against a selection of old geezers plus Max! And then the castle is haunted and a new case begins...

The story is about a boy named Kalle Blomkvist who with his friends solves crimes. But also play the battle between the red rose and the white rose with his rival friends. But everything changes when Kalle Blomkvists friend finds a dead man in a cabin and then must his friends and he find the murdurer.

Late one night, Billy and Kade Ruckman see their neighbor, Michael Chambers, murder a woman, but Chambers has a story all set to convince their mother Vicky, that it was just a rehearsal scene from an opera. The only ones who can help them find the body in Chambers' house before he moves and gets rid of all evidence, are their friends, Jimmy, Eddie, and J.J., who are determined to find the body before Chambers finds them.

Pinky, a child detective, solves two cases for multi-millionaire Jonathan Morgan.

A wealthy student with too much fashion sense, her equally rich friends, and her rival/superior from the school paper work together to solve the case when their teacher goes missing.

Three friends find a secret tunnel under the ruins of a church that leads them to the basement of a dilapidated house and, incidentally, a group of counterfeiters.

The Viennese detective children Biggi, Patrick and Luke find a key in dragon form, and their curiosity is aroused. They realize that the sinister Lady Q is interested in opening the legendary moon palace and find the elixir which is believed that promises eternal youth. The Tigers must prevent that Lady Q enters into possession of the priceless liquid.

Susie is an awkward college student who seizes the opportunity to bolster her popularity and her under-the-radar true-crime podcast by attempting to solve the disappearance of a classmate.

Valo, who recently moved to Raahe, gets bullied. After rescuing an abandoned dog, Valo finds a friend in it, whom she names Roi. Together, the friends end up investigating the mysterious disappearance of a neighbor boy.

Emil is spending his summer vacation with his grandmother in Berlin. But on the train there, he is robbed by the ruthless con artist Max Grundeis and a wild adventure begins! Together with his friends Pony, Gustav, Dienstag, Anh, and Jason, Emil sets off in pursuit and embarks on a fast-paced detective hunt across Berlin.

Henkka Virtanen finds evidence of a possible crime on his way to school. With his friend J.K. Kivimutka, the boys decide to investigate what has happened, because these criminal cases are the responsibility of the detective agency they have set up. When it turns out that mailboxes in the area have disappeared during the night, the detective bureau has already two crimes to solve. A fun and exciting adventure begins, in which the boys also have to face their own fears.