  We report the discovery of giant (50-100 kpc) [O II] emitting nebulae with
the Multi-Unit Spectroscopic Explorer (MUSE) in the field of TXS 0206-048, a
luminous quasar at z=1.13. Down-the-barrel UV spectra of the quasar show
absorption at velocities coincident with those of the extended nebulae,
enabling new insights into inflows and outflows around the quasar host. One
nebula exhibits a filamentary morphology extending over 120 kpc from the halo
toward the quasar and intersecting with another nebula surrounding the quasar
host with a radius of 50 kpc. This is the longest cool filament observed
to-date and arises at higher redshift and in a less massive system than those
in cool-core clusters. The filamentary nebula has line-of-sight velocities >300
km/s from nearby galaxies but matches that of the nebula surrounding the quasar
host where they intersect, consistent with accretion of cool inter- or
circum-galactic medium or cooling hot halo gas. The kinematics of the nebulae
surrounding the quasar host are unusual and complex, with redshifted and
blueshifted spiral-like structures. The emission velocities at 5-10 kpc from
the quasar match those of inflowing absorbing gas observed in UV spectra of the
quasar. Together, the extended nebulae and associated redshifted absorption
represent a compelling case of cool, filamentary gas accretion from halo scales
into the extended interstellar medium and toward the nucleus of a massive
quasar host. The inflow rate implied by the combined emission and absorption
constraints is well below levels required to sustain the quasar's radiative
luminosity, suggesting anisotropic or variable accretion.
