  We describe progress in a programme to study a sample of sources typical of
those which contribute a large fraction of the hard X-ray background. The
sources are selected from the fields of approximately 10 ks Chandra cluster
observations with follow-up in the near-infrared and optical. The X-ray data
indicate that many of these are powerful, obscured sources. Two hard objects
which are lensed by the cluster are good candidates for X-ray type-2 quasars,
with luminosities of the order 10^{44}-10^{45} erg s^{-1} and obscuring column
densities of the order 10^{23} cm^{-2}. We find that the sources are bright in
the infra-red (K typically 17-18). From Keck optical spectra and photometric
redshifts, we find that the host galaxies are consistent with being early-type,
massive hosts at redshifts ranging from 0.2 to 3, with median redshift
approximately 1.5. The two obscured quasars also have mid-infrared detections
and 850-micron upper-limits implying that the surrounding dust is at
warm-to-hot temperatures (T of the order of 1000 K).
