She pauses at the door, and then knocks three times. 'Come in,' says the stern voice inside immediately. She takes a deep breath, steadying herself, and then opens the door.
McGonagall looks over at her from her desk, over some Transfiguration homework. 'Very well, Miss Montague,' she says, saying nothing about her lateness. She gets up, putting on a traveling cloak. 'We are expected at the Ministry.'
McGonagall moves over to her fireplace, throwing Floo powder into the fireplace, turning the fire green. Leo sighs and she moves over to the fire, stepping inside. 'The Ministry of Magic,' she says clearly, and disappears in a whirl of colour.