  A search for heavy resonances decaying to a pair of Z bosons is performed
using data collected with the CMS detector at the LHC. Events are selected by
requiring two oppositely charged leptons (electrons or muons), consistent with
the decay of a Z boson, and large missing transverse momentum, which is
interpreted as arising from the decay of a second Z boson to two neutrinos. The
analysis uses data from proton-proton collisions at a center-of-mass energy of
13 TeV, corresponding to an integrated luminosity of 35.9 fb$^{-1}$. The
hypothesis of a spin-2 bulk graviton (X) decaying to a pair of Z bosons is
examined for 600 $\le m_\mathrm{X} \le$ 2500 GeV and upper limits at 95%
confidence level are set on the product of the production cross section and
branching fraction of X $\to$ ZZ ranging from 100 to 4 fb. For bulk graviton
models characterized by a curvature scale parameter $\tilde{k} =$ 0.5 in the
extra dimension, the region $m_\mathrm{X} < $ 800 GeV is excluded, providing
the most stringent limit reported to date. Variations of the model considering
the possibility of a wide resonance produced exclusively via gluon-gluon fusion
or $\mathrm{q}\overline{\mathrm{q}}$ annihilation are also examined.
