A silver-nanowire cavity is functionalized with CdSe nanocrystals and optimized towards cavity quantum electrodynamics by varying the nanocrystal-nanowire distance $d$ and cavity length $L$. From the modulation of the nanocrystal emission by the cavity modes a plasmon group velocity of $v_{\mathrm{gr}}\sim 0.5c$ is derived. Efficient exciton-plasmon-photon conversion and guiding is demonstrated along with a modification in the spontaneous emission rate of the coupled exciton-plasmon system.