  Dusty, star-forming galaxies have a critical role in the formation and
evolution of massive galaxies in the Universe. Using deep far-infrared imaging
in the range 100-500um obtained with the Herschel telescope, we investigate the
dust-obscured star formation in the galaxy cluster XDCP J0044.0-2033 at z=1.58,
the most massive cluster at z >1.5, with a measured mass M200= 4.7x10$^{14}$
Msun. We perform an analysis of the spectral energy distributions (SEDs) of 12
cluster members (5 spectroscopically confirmed) detected with >3$\sigma$
significance in the PACS maps, all ULIRGs. The individual star formation rates
(SFRs) lie in the range 155-824 Ms/yr, with dust temperatures of 24$\pm$35 K.
We measure a strikingly high amount of star formation (SF) in the cluster core,
SFR (< 250 kpc) > 1875$\pm$158 Ms/yr, 4x higher than the amount of star
formation in the cluster outskirts. This scenario is unprecedented in a galaxy
cluster, showing for the first time a reversal of the SF-density relation at
z~1.6 in a massive cluster.
