This　paper　is　concerned　with　the　global　dynamics　of　a　continuous　planar　piecewise　linear　differential　system　with　three　zones,　where　the　dynamic　of　the　one　of　the　exterior　linear　zones　is　saddle　and　the　remaining　one　is　anti-saddle.　We　give　all　global　phase　portraits　in　the　Poincaré　disc　and　the　complete　bifurcation　diagram　including　boundary　equilibrium　bifurcation　curves,　degenerate　boundary　equilibrium　bifurcation　curves,　homoclinic　bifurcation　curves　and　double　limit　cycle　bifurcation　curves.　Its　application　in　a　second-order　memristor　oscillator　is　shown.　Finally,　some　numerical　phase　portraits　are　demonstrated　to　illustrate　our　theoretical　results.　©　2022,　The　Author(s),　under　exclusive　licence　to　Springer　Nature　B.V.