Pluto and Neptune orbits are not in the same plane.
Jason asks: "Since Pluto's orbit intersects Neptune's orbit, will Pluto ever crash into Neptune or become one of Neptune's moons?"
Answer: No. From 1979 to 1999, Pluto was the eighth planet from the sun. In 1999, it slipped beyond Neptune to become the ninth.
For the rest of the story: http://www.lifeslittlemysteries.com/420-will-pluto-ever-hit-neptune.html