  We study the melting of a domain wall in a free-fermionic chain with a
localised impurity. We find that the defect enhances quantum correlations in
such a way that even the smallest scatterer leads to a linear growth of the
entanglement entropy contrasting the logarithmic behaviour in the clean system.
Exploiting the hydrodynamic approach and the quasiparticle picture, we provide
exact predictions for the evolution of the entanglement entropy for arbitrary
bipartitions. In particular, the steady production of pairs at the defect gives
rise to non-local correlations among distant points. We also characterise the
subleading logarithmic corrections, highlighting some universal features.
