The Precision Reactor Oscillation and SPECTrum (PROSPECT) experiment is a short-baseline reactor experiment with the goal of measuring the antineutrino spectrum from the High Flux Isotope Reactor (HFIR). It searches for potential short-baseline oscillations and the existence of sterile neutrinos. PROSPECT has already set new limits on the existence of eV-scale sterile neturinos while achieving the highest signal-to-background ratio on any surface antineutrino detector. Despite the achievements so far, progress remains to be made. The collaboration has developed an upgraded detector design, called PROSPECT-II, which will increase the detector's statistics and sensitivity. PROSPECT-II will probe a unique oscillation parameter space at high mass splittings. The measurements will provide new insight into the discrepancies between the predicted and observed reactor antineutrino spectrum. This poster will describe the design of the PROSPECT-II detector and its extended physics program.