Johan is a purely documentary film that shows the therapy undergone by a patient suffering from aphasia. Aphasia is an illness that affects the language centre of the brain and that can be generated by, amongst other things, a cerebral tumour or haemorrhage. Patients suffering from aphasia are often subject to chronic memory loss and, as a result of the ensuing semantic or interpretative disturbances, they cannot recognise certain specific objects as such or correctly categorise them.