  A model-independent search for direct CP violation in the Cabibbo suppressed
decay $D^+ \to K^- K^+\pi^+$ in a sample of approximately 370,000 decays is
carried out. The data were collected by the LHCb experiment in 2010 and
correspond to an integrated luminosity of 35 pb$^{-1}$. The normalized Dalitz
plot distributions for $D^+$ and $D^-$ are compared using four different
binning schemes that are sensitive to different manifestations of CP violation.
No evidence for CP asymmetry is found.
