Quantum calculations are reported for the high-resolution spectra and dynamics of the first and second overtone of the acetylenic C-H stretch (nu(1)) in propyne. The calculational method used is similar to that we have-used Lack of low-order Fermi resonances lead to a vibrational superexchange mechanism of decay of the initially populated bright state. The importance; of the total density of states and quartic couplings between zeroth-order states is investigated. Comparison with recent experimental results is discussed.