Illustration of the story 'That Which Went Away,' by Mark Wright, from the Doctor Who Short Trips collection Seven Deadly Sins.

"The Doctor put his arms around Zoe and Aella and he swept them to the side of the rocky hollow. Hefn turned the bowl upside down. The Doctor, Zoe and Aella ducked down into an overhang of rock. Blood splattered in thick rivulets over Hefn's face and chin.
"Don't look!" commanded the Doctor.
All around, the thanes began to convulse, their skin flowing and bubbling. Bones began to crack and pop, lengthening and changing, muscles being ripped away and reformed, bound with gristle and sinew. Zoe screamed as she saw Jamie, his entire body contorted out of shape, reforming before her eyes. The Doctor put a comforting hand on her shoulder.
The Doctor looked around, horror replaced with curiosity. A fizzing,
popping sound echoed around the hollow and began to drown out the brutal sound of transformation. The Doctor glanced furtively from side to side, his eyes coming to rest on Bior, who appeared to be the source of the sound.
Where the drighten had stood seconds before was a half-man, half-beast as he too was caught in the grip of the change, but something different was happening to him. As he became more bear than man, his back arching over with powerful muscle, his entire body began to glow a deep, burning red. The air around him began to shimmer and haze, as if he were drawing energy from the very air, the fizzing shifting into an angry buzzing, growing in intensity with every passing second."