  The fate of a massive star during the latest stages of its evolution is
highly dependent on its mass-loss history and geometry, with the yellow
hypergiants being key objects to study those phases of evolution. We present
near-IR interferometric observations of the famous yellow hypergiant IRC +10420
and blue spectra taken between 1994-2019. Our 2.2 $\mu$m GRAVITY/VLTI
observations attain a spatial resolution of $\sim$5 stellar radii and probe the
hot emission in the K-band tracing the gas via Na i double emission and the
Br$\gamma$ emission. The observed configurations spatially resolve the 2.2
$\mu$m continuum as well as the Br$\gamma$ and the Na i emission lines. Our
geometric modelling demonstrates the presence of a compact neutral zone (Na i)
which is slightly larger than the continuum but within an extended Br$\gamma$
emitting region. Our geometric models of the Br$\gamma$ emission confirm an
hour-glass geometry of the wind. To explain this peculiar geometry we
investigate the presence of a companion at 7-800 au separations and find no
signature at the contrast limit of our observations (3.7 mag at 3$\sigma$). We
report an evolution of the ejecta over a time span of 7 years, which allows us
to constrain the opening angle of the hour-glass geometry at $<$10$^\circ$.
Lastly, we present the first blue optical spectra of IRC +10420 since 1994. The
multi-epoch data indicate that the spectral type, and thus temperature, of the
object has essentially remained constant during the intervening years. This
confirms earlier conclusions that following an increase in temperature of 2000
K in less than two decades prior to 1994, the temperature increase has halted.
This suggests that this yellow hypergiant has "hit" the White Wall in the
HR-diagram preventing it from evolving blue-wards, and will likely undergo a
major mass-loss event in the near future.
