  We explore the challenging but phenomenologically interesting hierarchical
mass spectrum of the Inert Doublet Model where relatively light dark matter
along with much heavier scalar states can fully satisfy the constraints on the
relic abundance and also fulfill other theoretical as well as collider and
astrophysical bounds. To probe this region of parameter space at the LHC, we
propose a signal process that combines up to two large radius boosted jets
along with substantial missing transverse momentum. Aided by our intuitive
signal selection, we capture a hybrid process where the di-fatjet signal is
significantly enhanced by the mono-fatjet contribution with minimal effects on
the SM di-fatjet background. Substantiated by the sizable mass difference
between the scalars, these boosted jets, originally produced from the hadronic
decay of massive vector bosons, still carry the inherent footprint of their
root. These features implanted inside the jet substructure can provide
additional handles to deal with a large background involving QCD jets. We adopt
a multivariate analysis using boosted decision tree to provide a robust
mechanism to explore the hierarchical scenario, which would bring almost the
entire available parameter space well within reach of the 14 TeV LHC runs with
high luminosity.
