  We present optical and near-infrared integral field spectroscopy of the SCUBA
galaxy SMM J163650.43+405734.5 (ELAIS N2 850.4) at z=2.385. We combine Ly-alpha
and H-alpha emission line maps and velocity structure with high resolution HST
ACS and NICMOS imaging to probe the complex dynamics of this vigorous
star-burst galaxy. The imaging data shows a complex morphology, consisting of
at least three components separated by ~1'' (8kpc) in projection. When combined
with the H-alpha velocity field from UKIRT UIST IFU observations we identify
two components whose redshifts are coincident with the systemic redshift,
measured from previous CO observations, one of which shows signs of AGN
activity. A third component is offset by 220+/-50km/s from the systemic
velocity. The total star formation rate of the whole system (estimated from the
narrow-line H-alpha and uncorrected for reddening) is 340+/-50Mo/yr. The
Ly-alpha emission mapped by the GMOS IFU covers the complete galaxy and is
offset by +270+/-40km/s from the systemic velocity. This velocity offset is
comparable to that seen in rest-frame UV-selected galaxies at similar redshifts
and usually interpreted as a star-burst driven wind. The extended structure of
the Ly-alpha emission suggests that this wind is not a nuclear phenomenon, but
is instead a galactic scale outflow. Our observations suggest that the vigorous
activity in N2 850.4 is arising as a result of an interaction between at least
two dynamically-distinct components, resulting in a strong starburst, a
starburst-driven wind and actively-fuelled AGN activity. [abridged]
