A Night to Remember

You walk into the kitchen to pour a new drink. You open the cabinet and right next to the glasses, you see a powdery substance. You quickly put everything together in your head. Katie walked over to the guy and put some drugs in his drink. You start freaking out and you soon realize you have to do something quickly. You decide your best option would be to call the cops. If you call the cops you could risk losing your best friend, but if you Katie could harm many more people. People's lives are in danger, what do you do?