  G23.33-0.30 is a 600 $M_{\odot}$ infrared dark molecular filament that
exhibits large NH$_3$ velocity dispersions ($\sigma \sim 8 \ \rm{km \ s^{-1}}$)
and bright, narrow NH$_3$(3,3) line emission. We have probed G23.33-0.30 at the
$<0.1$ pc scale and confirmed that the narrow NH$_3$(3,3) line is emitted by
four rare NH$_3$(3,3) masers, which are excited by a large-scale shock
impacting the filament. G23.33-0.30 also displays a velocity gradient along its
length, a velocity discontinuity across its width, shock-tracing SiO(5-4)
emission extended throughout the filament, broad turbulent line widths in
NH$_3$(1,1) through (6,6), CS(5-4), and SiO(5-4), as well as an increased
NH$_3$ rotational temperature ($T_{\rm{rot}}$) and velocity dispersion
($\sigma$) associated with the shocked, blueshifted component. The correlations
among $T_{\rm{rot}}$, $\sigma$, and $V_{\rm{LSR}}$ implies that the shock is
accelerating, heating, and adding turbulent energy to the filament gas. Given
G23.33-0.30's location within the giant molecular cloud G23.0-0.4, we speculate
that the shock and NH$_3$(3,3) masers originated from the supernova remnant
W41, which exhibits additional evidence of an interaction with G23.0-0.4. We
have also detected the 1.3 mm dust continuum emission from at least three
embedded molecular cores associated with G23.33-0.30. Although the cores have
moderate gas masses ($M = 7-10$ M$_{\odot}$), their large virial parameters
($\alpha=4-9$) suggest that they will not collapse to form stars. The turbulent
line widths of the cores may indicate negative feedback due to the SNR shock.
