  Mergers between a massive galaxy and a small gas-rich companion (minor
mergers) have been proposed as a viable mechanism for triggering radio emission
in an active galaxy. Until now the problem has been catching this sequence of
events as they occur. With MRC B1221$-$423 we have an active radio galaxy that
has only recently been triggered, and a companion galaxy that provides the
"smoking gun". Using spectroscopic data taken with the VIMOS Integral Field
Unit detector on the European Southern Observatory's Very Large Telescope, we
have examined the distribution, ionization state and kinematics of ionized gas
in this interacting system. We have also modelled the stellar continuum with
synthesised spectra of stellar populations of different ages. From our study of
the ionized gas, we have derived preliminary models for the geometry of the
interaction, analysed the kinematic behaviour of the ionized gas, and examined
the ionization mechanisms at work throughout the system. Our modelling of the
stellar continuum allowed us to identify and date distinct stellar populations
within the galaxy pair. We find evidence of multiple episodes of widespread
starburst activity, and by dating these populations, we provide tentative
insight into the history of the interaction.
