Light curve and spectral parameter evolution of V404 Cyg during the December 2015 outburst. Top panel: 20–65 keV INTEGRAL/ISGRI light curve, scaled to Crab units. Red symbols are used for the flares. Second panel: 2–10 keV fluxes (in Crab units) from the individual Swift/XRT snapshots. Blue circles indicate data used to extract the non-flaring spectra. Third panel: photon index; the black symbols indicate the spectra accumulated by averaging the Swift and INTEGRAL non-flaring emission. Bottom panel: electron temperatures from the NTHCOMP model fits.