The results of a leading-order QCD analysis of neutrino-induced charm production are presented. They are based on a sample of 4111 $\numu$- and 871 $\anumu$-induced opposite-sign dimuon events with $E_{\mu 1},E_{\mu 2} 6~{\rm GeV}$, $35 E_{\nu} 290~{\rm GeV}$ and $Q^2 5.5\,{\rm GeV^2}$, observed in the CHARM~II detector exposed to the CERN wideband neutrino and antineutrino beams. The analysis yields the value of \linebreak the charm quark mass $m_c=1.79\pm0.38\,{\rm GeV}/c^2$ and the Cabibbo--Kobayashi--Maskawa matrix element $|V_{cd}|=0.219\pm0.016$. The strange quark content of the nucleon is found to be suppressed with respect to non-strange sea quarks by a factor $\kappa =0.39\pm0.09$.