Becky Ripley and Emily Knight celebrate the intelligence of a brainless slime mould. As single-cell protists, with no brain and no nervous system, slime moulds do not 'think' in human terms, but they can calculate and navigate complex systems with incredible efficiency and objectivity. With some help from a few oat flakes, because slime mould loves oats. One species in particular, Physarum Polycephalum, has proven itself to outwit us time and time again, from solving complex urban transport problems to mapping the structures of the cosmic web. In doing so, it totally overthrows our human definition of intelligence, where we have positioned ourselves at the top of a big biological hierarchy. From the bottom up, slime mould is starting to uproot the whole system. Featuring Merlin Sheldrake, writer of 'Entangled Life', and experimental philosopher Jonathon Keats.