Our proposal aims at microscopic investigation of magnetism of the novel copper-based low-dimensional spin system CuNCN, the first compound with a pure nitride environment of Cu2+. According to bulk susceptibility, heat-capacity and neutron diffraction measurements, this system lacks conventional long-range magnetic ordering, at least down to 1.8 K, despite extremely large Heisenberg exchange coupling, as predicted by DFT calculations. One on the existing theories explains the magnetic properties of CuNCN within a resonating-valence-bond (RVB) framework. The prediction of the RVB ground state, however, needs to be verified experimentally by a highly sensitive local-probe technique down to the lowest accessible temperatures. Beyond determining the ground state of this novel compound, our study might help understanding better the fascinating field of disordered quantum states of matter.