The presence of a binary companion can have a significant effect on a supernova
explosion.  Mass transfer affects the evolution of the stars; a massive star
may transfer so much mass that it fails to explode as a supernova, whilst
conversely an accreting lower-mass star may gain enough material to cause it to
explode.  Massive stellar cores in close binaries can be spun up by their
companions and this may be a source of the rapidly-rotating hypernova
explosions that power gamma-ray bursts.  Another possible source of gamma-ray
bursts in binaries is the deflection of supernova ejecta that are falling back
on to a newly-formed black hole.  We present some of our recent work on
modelling these processes, in order to understand supernovae in interacting
binaries and their relation to gamma-ray bursts.