A study of the blue compact dwarf ( BCD ) galaxy Mrk 996 based on high resolution optical VLT VIMOS integral field unit spectroscopy is presented . Mrk 996 displays multi-component line emission , with most line profiles consisting of a narrow , central Gaussian ( FWHM \sim 110 km s ^ { -1 } ) with an underlying broad component ( FWHM \sim 400 km s ^ { -1 } ) . The broad H i Balmer component splits into two separate broad components inside a 1 ^ { \prime \prime } .5 radius from the nucleus ; these are attributed to a two-armed mini-spiral . This spiral-like nucleus rotates in the same sense as the extended narrow-line ionised gas but is offset by \sim 50 km s ^ { -1 } from the systemic velocity of the galaxy . The rotation curve of Mrk 996 derived from the H \alpha narrow component yields a total mass of 5 \times 10 ^ { 8 } M _ { \odot } within a radius of 3 kpc . From the H \alpha luminosity we infer a global star formation rate of \sim 2 M _ { \odot } yr ^ { -1 } . The high excitation energy , high critical density [ O iii ] \lambda 4363 and [ N ii ] \lambda 5755 lines are only detected from the inner region and exist purely in broad component form , implying unusual excitation conditions . Surface brightness , radial velocity , and FWHM maps for several emission components are presented . A separate physical analysis of the broad and narrow emission line regions is undertaken . We derive an upper limit of 10,000 K for the electron temperature of the narrow line gas , together with an electron density of 170 cm ^ { -3 } , typical of normal H ii regions . For the broad line component , measured [ O iii ] and [ Fe iii ] diagnostic line ratios are consistent with a temperature of 11,000 K and an electron density of 10 ^ { 7 } cm ^ { -3 } . The broad line emission regions show N/H and N/O enrichment factors of \sim 20 relative to the narrow line regions , but no He/H , O/H , S/H , or Ar/H enrichment is inferred . Previous studies indicated that Mrk 996 showed anomalously high N/O ratios compared with BCDs of a similar metallicity . Our multi-component analysis yields a revised metallicity of \geq 0.5 Z _ { \odot } ( 12 + log O/H = 8.37 ) for both the narrow and broad gas components , significantly higher than previous studies . As a result the narrow line region ’ s N/O ratio is now typical for the galaxy ’ s metallicity . The narrow line component ’ s N/O ratio peaks outside the core region , spatially correlating with \sim 3 Myr-old stellar populations . The dominant line excitation mechanism is photoionisation by the \sim 3000 WR stars and \sim 150,000 O-type stars estimated to be present in the core . This is indeed a peculiar BCD , with extremely dense zones of gas in the core , through which stellar outflows and possible shock fronts permeate contributing to the excitation of the broad line emission .