ICH MUSS DIR WAS SAGEN is a documentary film about the 4-year old twin brothers Oskar and Leo. Oskar has been deaf since birth, Leo has unimpaired hearing. Both are growing up with a shared language that develops in silence: sign language. Over the course of a year the young filmmaker Martin Nguyen has observed the twins from up close and from their perspective, watching them grow and discover a world that they are getting to know through sign language. The film examines what the diagnosis "deaf" means to Oskar's hearing parents, Sandra and Stefan. The cochlear implant that could enable Oskar to hear has been an issue since his birth, but for the time being his parents have decided to take sign language classes and to raise the children in what is for them a foreign language. Leo is being brought up bilingual, with sign language and spoken language. For Oskar, however, sign language is his essential form of expression - his mother tongue.