  The first search for scalar leptoquarks produced in $\tau$-lepton-quark
collisions is presented. It is based on a set of proton-proton collision data
recorded with the CMS detector at the LHC at a center-of-mass energy of 13 TeV
corresponding to an integrated luminosity of 138 fb$^{-1}$. The reconstructed
final state consists of a jet, significant missing transverse momentum, and a
$\tau$ lepton reconstructed through its hadronic or leptonic decays. Limits are
set on the product of the leptoquark production cross section and branching
fraction and interpreted as exclusions in the plane of the leptoquark mass and
the leptoquark-$\tau$-quark coupling strength.
