Paris breaks the warp-ten barrier with unexpected results.
Tom Paris pilots a shuttle past warp 10 and appears to have broken the transwarp barrier, but the achievement comes with a strange and dangerous side effect that changes his body. The crew must work out what is happening to him before the damage becomes permanent.
The episode is one of the most controversial in the series and is often cited by fans as a low point. It is notable for its ambitious science-fiction idea of a speed beyond all limits, and for the unusual and surprising place the story eventually goes, which people still discuss decades later.