It is 1903. Thomas Edgar, a passionate collector of butterflies, is offered the chance of a lifetime: to travel to the Amazon as part of a scientific expedition to find the mythical butterfly that will make his name. But on his return, his wife Sophie is appalled by the change in him: he is thin, obviously sick, and apparently so traumatised by what he has witnessed, he has been rendered mute. As Thomas struggles to find the words to describe what he's seen, it's unclear whether or not Sophie - and their marriage - will be able to withstand what he has to tell her, for the story that unfolds, the story behind Thomas's silence, is one of great brutality.