|Need To Know|
|Season 6, Episode 3|
|Air date||October 7, 2013|
|Written by||Elizabeth Beall|
|Directed by||Larry Shaw|
With Beckett still in D.C., Castle and the boys investigate the murder of former child star Charlie Reynolds, who rose to fame playing the lovable nerd on an early 90s High School sitcom. But the case takes a turn for the strange when Agents Beckett and McCord arrive from Washington to take over the investigation, creating competitive tension in the precinct. But why would a washed-up actor's death warrant Federal scrutiny? Whatever the reason, Beckett and McCord aren't telling. Meanwhile, Castle has to contend with a new face at the 12th, NYPD Detective Grant "Sully" Sullivan (Joshua Bitton, "The Pacific").
- Nathan Fillion as Richard Castle
- Stana Katic as Detective Kate Beckett
- Jon Huertas as Detective Javier Esposito
- Seamus Dever as Detective Kevin Ryan
- Tamala Jones as Dr. Lanie Parish (credited only)
- Penny Johnson Jerald as Captain Victoria Gates
- Molly C. Quinn as Alexis Castle
- Susan Sullivan as Martha Rodgers
- Lisa Edelstein as Rachel McCord
- Antonio Sabato, Jr. as Ramon Russo
- Arye Gross as Sidney Perlmutter
- Joshua Bitton as Grant Sullivan
- James Patrick Stuart as Ethan Wright
- Emily Foxler as Svetlana Renkov
- Alan Blumenfeld as Hank Harper
- Ruth Williamson as Geraldine Powers
- Jon Paul Burkhart as Potential Dewey
- Jeff Grace as Charlie Reynolds
- Nick Gracer as Vlad Bardinov
- Kiyano La'vin as Construction Worker
- Myko Olivier as Pi
- Jennifer Jean Snyder as Reporter
- Castle: This is a high profile case. And I am willing to let you guys exclusively benefit from my out-of-the-box crime solving mind.
- Esposito: And what do you get?
- Castle: Escape from the life in the loft.
- Perlmutter: Mr. Castle, you’re back, but not by popular demand.
- Rachel McCord: Kate, you’re one of the best agents I’ve ever worked with, but I’m here to tell you you’re fired.
- This episode introduces a new detective in homicide named Grant Sullivan, whose nickname is Sully.
- This is the last episode that Beckett was federal government agent before being fired at the end of the episode.
- The fictional show "2 Cool For School" seems to share traits with a number of sitcoms, such as "Saved by the Bell" and "Family Matters".
- The "Heat Wave" movie is mentioned for the first time since season 3, To Love and Die in L.A., we find out it went straight to DVD.
- Beckett helps the victim's girlfriend escape from being as a spy for the CIA, which cost her the Department of Justice job.
- A special feature on the Castle season 6 DVD set includes an audio commentary for this episode from Jon Huertas and Seamus Dever in-character as Esposito and Ryan.