  Dark Matter and Dark Energy are two of the most fundamental open questions in
physics today. The existence of a light dark-force mediator has been
hypothesized as a possible explanation for several unexplained physical
phenomena. A new search for this mediator, the dark photon $U$, is underway
using data collected with the KLOE detector at DA$\Phi$NE. We describe the
strategy we will use in our search for a resonant peak in the electron-positron
invariant mass spectrum from the process $e^+e^- \to U \gamma$ with $U \to
e^+e^-$. So far we found no evidence for the process and set a preliminary
upper limit on the level of mixing between the secluded dark sector and the
standard model.
