  Here we prove unitarity of the recently found fourth-order self-dual model of
spin-2 by investigating the analytic structure of its propagator. The model
describes massive particles of helicity +2 (or -2) in $D=2+1$ and corresponds
to the quadratic truncation of a higher derivative topologically massive
gravity about a flat background. It is an intriguing example of a theory where
a term in the propagator of the form $1/\lbrack\Box^2 (\Box - m^2)\rbrack $
does not lead to ghosts. The crucial role of the linearized Weyl symmetry in
getting rid of the ghosts is pointed out. We use a peculiar pair of gauge
conditions which fix the linearized reparametrizations and linearized Weyl
symmetries separetely.
