  Direct detection bounds are beginning to constrain a very simple model of
weakly interacting dark matter---a Majorana fermion with a coupling to the $Z$
boson. In a particularly straightforward gauge-invariant realization, this
coupling is introduced via a higher-dimensional operator. While attractive in
its simplicity, this model generically induces a large $\rho$ parameter. An
ultraviolet completion that avoids an overly large contribution to $\rho$ is
the singlet-doublet model. We revisit this model, focusing on the Higgs blind
spot region of parameter space where spin-independent interactions are absent.
This model successfully reproduces dark matter with direct detection mediated
by the $Z$ boson, but whose cosmology may depend on additional couplings and
states. Future direct detection experiments should effectively probe a
significant portion of this parameter space, aside from a small coannihilating
region. As such, $Z$-mediated thermal dark matter as realized in the
singlet-doublet model represents an interesting target for future searches.
