The T2K (Tokai to Kamioka) experiment is a collaboration of 400 physicists from 12 countries studying the behaviour of a particle called the neutrino. What makes it so elusive? Unlike other fundamental particles, the neutrino only interacts via the weak force. In practice, this means that neutrinos almost never interact. Hence, they typically travel through enormous amounts of matter leaving no information behind. Despite that, physicists have engaged in the challenge of finding and measuring the unusual and surprisingly influential properties of this ghostly particle.