  We present a fully differential next-to-next-to-leading order calculation of
charm quark production in charged-current deep-inelastic scattering, with full
charm-quark mass dependence. The next-to-next-to-leading order corrections in
perturbative quantum chromodynamics are found to be comparable in size to the
next-to-leading order corrections in certain kinematic regions. We compare our
predictions with data on dimuon production in (anti-)neutrino scattering from a
heavy nucleus. Our results can be used to improve the extraction of the parton
distribution function of a strange quark in the nucleon.
