A young motorcycle rider who wants to become a police detective but suddenly 5 people are killed and the killer is unknown and if he solves this case he can become a detective.

Totally agree with DPG. You can't convince an audience that the entry exam for any police force anywhere in the world is to solve a quintuple murder.

Beyond that ... young tells me next to nothing about your protagonist. What is the flaw?

Could you strengthen the stakes? Make it less about the job and more personal/primal?

"An ex-biker turned detective defies an apathetic police force to seek vengeance on his brother's murderers during a gang war."

The reel world of cinema can take liberties with the real world -- but not like this premise. In the real world, the character has to join the force as a rookie cop, get the training, work and study his way up the ranks.

The reel world of cinema can take liberties with the real world -- but not like this premise. In the real world, the character has to join the force as a rookie cop, get the training, work and study his way up the ranks.