99% of the plastic that should be floating in the oceans is missing. Even accounting for the plastic that washes up on beaches or is trapped in arctic ice, millions of tonnes has simply disappeared. As most plastic never deteriorates, it simply breaks down into smaller and smaller particles that are invisible to the human eye, what happens to this missing ocean plastic is a mystery. In this investigation, scientists embark in search of the micro-plastics. Small, mostly invisible, toxic, they are home to a new ecosystem: the plastisphere. But where are they? Ingested by organisms? Buried under the ocean floor? Degraded by bacteria? And what is the impact of them entering the food chain?