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.

“Need to Know” takes a look at Rick’s feelings about being left out of investigating and what when Kate returns to take a case way from Ryan and Esposito.

Kate and Rick seem to be sustaining themselves on video chat but is it really enough to sustain their relationship long term?

Rick is also dealing with Alexis’ live in boyfriend, Pi, who seems insistent on making smoothies and annoying Rick to no end.

While Rick is pouting, he catches the morning news and sees the old team on a murder case. Rick decides to join Esposito and Ryan who are less than willing to have him around. Sullivan is Kate’s replacement, and he is definitely different.

The murder victim is a caricature of Screech from Saved by the Bell but before Rick and the others can even start to investigate, Kate and McCord show up and take over the case. They won’t tell the others why and a line is drawn between Kate and her old team. There are some seriously funny moments between Esposito and Rick.

Esposito and Ryan put the pressure on Rick to get intel from Kate. He tries bribing her with a latte, but she is on to him.

Kate and McCord continue to investigate separately from the others who visit the secret movie set for 2 Cool for School. Ryan is the ultimate fanboy. They discover that the movie is being funded by the Russians where the show was very popular.

Rick, Esposito, and Ryan head to a warehouse looking for clues. They find guns hiding inside the camera cases for the show and within minutes of finding them Kate and McCord show up. Just after their arrival a CIA agent shows up. There were far too many guns being pointed in all directions.

The CIA puts a stop to the investigation which angers Esposito, Ryan and Rick. McCord and Gates face off regarding closing the case.

In the end Kate gives Rick the information for them to solve the case. Kate also leaks a tip to the press in order to save the victim.

Rick sits Kate down to have a serious talk in about their relationship and just when you think that they may not make it Rick says he bought an apartment for them in DC. The celebration is sort lived when McCord arrives to tell Kate she is fired for leaking information to the press.