  In the past five years, a flurry of X-ray reverberation lag measurements of
accreting supermassive black holes have been made using the XMM-Newton
telescope in the 0.3-10 keV energy range. In this work, we use the NuSTAR
telescope to extend the lag analysis up to higher energies for two Seyfert
galaxies, SWIFT J2127.4+5654 and NGC 1365. X-ray reverberation lags are due to
the light travel time delays between the direct continuum emission and the
reprocessed emission from the inner radii of an ionised accretion disc.
XMM-Newton has been particularly adept at measuring the lag associated with the
broad Fe K emission line, where the gravitationally redshifted wing of the line
is observed to respond before the line centroid at 6.4 keV, produced at larger
radii. Now we use NuSTAR to probe the lag at higher energies, where the
spectrum shows clear evidence for Compton reflection, known as the Compton
'hump'. The XMM-Newton data show Fe K lags in both SWIFT J2127.4+5654 and NGC
1365. The NuSTAR data provide independent confirmation of these Fe K lags, and
also show evidence for the corresponding Compton hump lags, especially in SWIFT
J2127.4+5654. These broadband lag measurements confirm that the Compton hump
and Fe K lag are produced at small radii. At low-frequencies in NGC 1365, where
the spectrum shows evidence for eclipsing clouds in the line of sight, we find
a clear negative (not positive) lag from 2--10 keV, which can be understood as
the decrease in column density from a neutral eclipsing cloud moving out of our
line of sight during the observation.
