Murder at Midnight

Bella heard the sound of a man approaching, so she hid under a desk. The door opened and in stepped a middle-aged man with neat brown hair and a moustache. The butler. He looked around, making sure nobody was there, and took the gun before going back out. Strange.
She didn't have time to think about it though as another person came in. A woman with black hair and black eyes. She also looked around, as the other man but instead of taking something she pulled out her phone, dialled a number, and said, 'It has been done. Potter is dead.' Then, she left.
--------------------------Bella Lacroix is one of the best detectives in the London police department. So when there is a murder, she actively tries to catch the real culprit while the police chase the red herring. But nothing is what it seems, and Bella will have to use it all to solve the murder at midnight.