A hybrid metamaterial-waveguide (HMW) system, consisting of a plasmon-induced transparency (PIT) metamaterial layer deposited on top of a slab waveguide, is investigated at mid-infrared wavelengths. The proposed hybrid system supports three quasi-guided modes. Two of them are excited through the conventional pathway, i.e. directly excited from the free-space waves via the diffractive coupling, while the theoretical analysis and numerical simulation both demonstrate that the third one undergoes a completely different excitation pathway, i.e. induced by the dark plasmon mode via near field coupling. The interactions between the three quasi-guided modes and the PIT effect further lead to the interesting multi-spectral transmission characteristics that cannot be realized in traditional HMW systems. This is the first report, to our best knowledge, describing this unconventional excitation mechanism of the quasi-guided mode as well as the interaction between the quasi-guided waveguide mode and PIT effect.