  We consider the setup of an evaporating black hole in AdS$_{4}$ coupled to an
external bath, embedded in type IIB string theory. We study quantum extremal
islands in these backgrounds, in relation to the existence of a massive
graviton. Using explicit results of the microscopic embedding of AdS$_{4}$
massive gravity in string theory, we investigate whether it is possible to
achieve backgrounds with extremal islands, in which the lowest lying graviton
is only slightly massive. For certain regions of the microscopic parameters,
the graviton mass can be computed explicitly, and we explain how it directly
affects the existence and the properties of the islands. We also show that
islands can in principle exist within the regime of validity of the massive
gravity effective field theory. However we see via numerical computations that
the existence of quantum extremal islands at zero temperature is highly
constrained, also when the dilaton is allowed to vary, so that the mass of the
graviton cannot be made arbitrarily light. At finite temperature, we also
identify a critical parameter, above and below which islands still exist but
exhibit a different behavior. Our work supports recent proposals that the
unitary evolution of black holes in higher dimensions, and more precisely their
Page curve, strongly relies on the presence of a massive graviton in the
effective theory.
