Terry knows the girl isn't actually there. Later in the Batcave, Bruce hooks Terry's brain up to a missing children's database. We learn that Tamara was taken by the two adults from her parents, who thought they were sending their daughter to a special school for mentally gifted students. Turns out the whole thing was a ruse by the Brain Trust so they could turn Tamara into a psychic warrior who'll do their evil bidding. Batman shows up in stealth mode, meaning he's invisible to the naked eye.
Batman tries to take the two adults on but their superpowers are intense.
It's not until Tamara steps up to the plate and throws a little mental heat of her own that the Bat's on even ground. Together the two new friends pound the evil adults into submission. Batman then returns Tamara to her parents. We assume that Terry's next task is to talk his history teacher into allowing him to retake that test. The Brain Trust, while still existing pretty much off our radar, would make a great group of villains to meet up with again.