  We present results from a {\em Chandra} observation of the cluster gas
associated with the FR II radio galaxy 3C 438. This radio galaxy is embedded
within a massive cluster with gas temperature $\sim$17 keV and bolometric
luminosity of 6$\times10^{45}$ ergs s$^{-1}$. It is unclear if this high
temperature represents the gravitational mass of the cluster, or if this is an
already high ($\sim$ 11 keV) temperature cluster that has been heated
transiently. We detect a surface brightness discontinuity in the gas that
extends $\sim$600 kpc through the cluster. The radio galaxy 3C 438 is too small
($\sim$110 kpc across) and too weak to have created this large disturbance in
the gas. The discontinuity must be the result of either an extremely powerful
nuclear outburst or the major merger of two massive clusters. If the observed
features are the result of a nuclear outburst, it must be from an earlier epoch
of unusually energetic nuclear activity. However, the energy required
($\sim10^{63}$ ergs) to move the gas on the observed spatial scales strongly
supports the merger hypothesis. In either scenario, this is one of the most
extreme events in the local Universe.
