Polly Walker will play a key role on The Mentalist Season 5.

The British actress (Rome, Caprica) will recur on the CBS drama as FBI Agent Alexa Shultz, described by Michael Ausiello of TV Line as "gorgeous, fierce and incredibly competent."

No word yet on exactly how this agent will fit into Patrick Jane's world, but we won't need to wait too long to find out.

Walker - a Golden Globe nominee - will debut on The Mentalist season premiere, scheduled for September 30.

Matt Richenthal is the Editor in Chief of TV Fanatic. Follow him on Twitter and on Google+.