The radiation shock dynamics of an accreting black hole is modeled, including nonadiabatic radiative losses and gains, heat transport processes, and pair processes in a simplified treatment. In the case of low specific angular momentum, self-consistent steady state solutions with shocks can exist in a spherical accretion flow, which for moderately supercritical accretion rates lead to radiation efficiencies of the order 0.01 and luminosities of the order 0.1 times the Eddington luminosity. To take a specific example, if the mass accretion rate is three times the critical rate, then the shock zone begins at about 80 Schwarzschild radii. The resulting luminosity, seen at infinity, is L(Edd)/20 and therefore, the efficiency is 10 to the -1.8. The positron density in the shock zone is about 20 percent of the protron density, and the Thompson optical depth of the zone is about 3. The temperature of the outgoing radiation is about 0.1 MeV. This mechanism is relevant for quasar and AGN models located in elliptical galaxies.