Adric saw the thread and followed it - at the end, he found the Doctor unraveling his scarf. It felt like a sad, final reminder that his Doctor was truly gone. This new Doctor was confused, babbling names Adric didn’t recognize as he stumbled deeper into the TARDIS. Adric followed, but noticed a distracting hum in the back of his mind, a sense that he was both here and someplace else.
The hum resolved into a familiar voice: “I am the Master and you will obey me!”
In horror, Adric remembered the coordinates he’d entered. Event One. He’d killed them all!