London 1897 and a young girl, Valentine Grey, arrives in England. She's been brought up in the remote and sunny climes of India and finds being forced into corsets and skirts in damp and cold country insufferable. The only bright spot: her exciting cousin, Reggie. Reggie, and his lover Frank seek out the adventure the clandestine bars and streets of London offer and are happy to include Valentine in their secret, showing her theatre, gardens - even teaching her how to ride a bicycle.
And then comes the Boer War and Reggie's father volunteers him; the empire must be defended. But it won't be Reggie who dons the Volunteer Regiment's garb. Valentine takes her chance, puts on her cousin's uniform, leaving Reggie behind and heads off to war. And for a long while it's glorious and liberating for both of the cousins, but war is not glorious and in Victorian London homosexuality is not liberating . . .