The BBC have released a story synopsis for the penultimate episode of Class, which is titled The Metaphysical Engine, or What Quill Did.
The synopsis contains spoilers.
With the gang trapped in detention and out of the way, Miss Quill accepts Dorothea’s astonishing offer: to help remove the Arn from her head, and to reclaim her freedom.
Alongside Ballon, an imprisoned shape-shifter, Miss Quill travels in a metaphysical engine and is taken to impossible, extraordinary and dangerous worlds, collecting materials in preparation for her life-changing procedure.
After an emotional encounter with her surgeon and a nearly-fatal operation, Miss Quill must find a way to return to Earth: transformed and ready for war.
The Metaphysical Engine, or What Quill Did drops on BBC Three on Saturday 26th November at 10am.