Professor Manteia looked upon Ford with a hardened stare. "I find your story difficult to believe Mr. Harkonnen, primarily as none of the other students that were found previously indicated anything about forming a search party to locate Bellatrix. I was also curious to know whether Miss Nix here had joined you in the forest as none of your fellow Slytherins mentioned anything about her being down at the Forbidden Forest."
Professor Manteia was growing increasingly concerned about the time being wasted on this conversation and the danger that Bellatrix might find herself in if they didn't locate her soon. Without waiting for a response, Professor Manteia flourished his wand and with a silent incantation cast Homenum Revelio in hopes of quickly locating Bellatrix. (see note about spell below if unfamiliar)
A moment later, the presence of the four Slytherin students he had previously banished to the Common Room were revealed nearby. Professor Manteia wheeled around at them, his normally stern, but stoic face now completely ablaze with anger. It had been a mistake for his students to have been caught wandering in and around the Forbidden Forest at night, but now they had disobeyed a direct order from their Head of House after he had told them that the Headmistress had been notified. Professor Manteia knew one thing, these students would always remember the night that they had betrayed his trust and embarrassed him in the eyes of the Headmistress.
He pointed his wand at them threateningly and said with a deadly serious tone. "You are all to proceed directly to the Slytherin Common Room AT ONCE!", he bellowed. "I expect that the Headmistress may already be there to greet you." Professor Manteia dropped his voice to a deadly whisper, "Should you wish to remain at this school, you will do as instructed immediately and without another word or I will see to it personally that you do not disgrace the name of Slytherin again...EVER!!!"
Professor Manteia turned to the forest and entered it at almost a full run, covering the ground swiftly and more gracefully than many would likely have believed him capable of. He disappeared from view intent on finding Bellatrix quickly and returning to the Slytherin Common Room before his students felt compelled to come up with any more ridiculous explanations for their behavior this evening.
Note: (from Wikipedia)
Homenum Revelio
Description: Reveals humans in the vicinity of the caster.
Seen/Mentioned: Used multiple times by various characters in Harry Potter and the Deathly Hallows.
Notes: It can be used non-verbally and without a wand (by Dumbledore anyway); Dumbledore does so to detect Harry underneath his Invisibility Cloak.[13].