Doctor Who: The Secret in Vault 13

A sinister school where graduation means death . . . A monstrous mystery lurking below a quiet London street . . . A desperate plea for help delivered by . . . hang on. A potted plant?The Doctor has been summoned. The galaxy is in terrible danger, and only a Time Lord can save it. But to do so, she must break in to an ancient vault on a remote and frozen world - from which nobody has ever returned alive . . . Can the Doctor and her friends Yaz, Ryan and Graham uncover the shocking secret in Vault 13?