  We report on the identification of a soft gamma-ray source, IGR J17204-3554,
detected with the IBIS imager on board the INTEGRAL satellite. The source has a
20-100 keV flux of ~3x10^-11 erg cm^-2 s^-1 and is spatially coincident with
NGC 6334, a molecular cloud located in the Sagittarius arm of the Milky Way.
Diffuse X-ray emission has been reported from this region by ASCA and
interpreted as coming from five far-infrared cores located in the cloud.
However, the combined ASCA spectrum with a 9 keV temperature was difficult to
explain in terms of emission from young pre-main sequence stars known to be
embedded in the star forming regions. Detection of gamma-rays makes this
interpretation even more unrealistic and suggests the presence of a high energy
source in or behind the cloud. Follow up observations with Swift and archival
Chandra data allow us to disentangle the NGC6334 enigma by locating an
extragalactic object with the proper spectral characteristics to explain the
gamma-ray emission. The combined Chandra/IBIS spectrum is well fitted by an
absorbed power law with index 1.2+/-0.1, NH=1.4+/-0.1x10^23 cm^-2 and an
unabsorbed 2-10 keV flux of 0.5x10^-11 erg cm^-2 s^-1. This column density is
in excess of the galactic value implying that we are detecting a background
galaxy concealed by the molecular cloud and further hidden by material located
either in the galaxy itself or between IGR J17204-3554 and the cloud.
