Answer:
A robber had just stole an expensive diamond and was being chased by the police through a building that was being constructed. Before he was caught by the police he hide the diamond in an air duct. Since he had remembered the building he had stashed the diamond in once he was out of jail he wanted to go retrieve the diamond. He returns to the location of his treasure and finds it is now a police station. He disguised himself as a recently transferred officer to infiltrate the building and the ending is up to you.
Step-by-step explanation: