  We present the results of a five-dimensional resonant amplitude analysis of
the $\Lambda_c^+{\to}pK^{-}\pi^{+}$ system based on $946\pm 38$ reconstructed
decays. These data were produced in 500 GeV/$c$ $\pi^-$-N interactions by
Fermilab experiment E791. We report measurements of the amplitudes for
$\Lambda_c^+$ decay into nonresonant $pK^-\pi^+$ and to $p\bar{K}^{*0}(890)$,
$\Delta^{++}(1232)K^-$, and $\Lambda(1520)\pi^+$ and we comment on other
possible resonant enhancements. This is the first complete amplitude analysis
of the $\Lambda_c^{+}{\to}pK^{-}\pi^{+}$ system. We find that
$(54.8\pm5.5\pm3.5)$% of the decays are nonresonant, $(19.5\pm2.6\pm1.8)$% of
the decays are via the $\bar{K}^{*0}$ resonance, $(18.0\pm2.9\pm2.9)$% of the
decays are via the $\Delta^{++}$ resonance, and $(7.7\pm1.8\pm1.1)$% of the
decays are via the $\Lambda(1520)$ resonance. We find evidence for an
increasingly negative polarization of the $\Lambda_c^+$ baryons as a function
of $p_T^2$, in agreement with a recent model\cite{dha} and with a related
measurement\cite{jez}.
