On Castle Season 5, a man who "may have" important information on the murder of Kate Beckett's murder is set to appear. Meanwhile, a former 'Gossip Girl' actress is also showing up next season.

Jack Coleman, the former Noah Bennet in the now-defunct series Heroes, will be seen as Beckett's main antagonist next season.

Jack Coleman: The man who may know something

Speaking to TV Line, 'Castle' creator and show runner Andrew Marlowe hinted Coleman could be one of those responsible for the death of Beckett's mother, as well as Montgomery.

"I can say that Jack Coleman plays somebody who has some knowledge about what may have gone on back in the day with Montgomery and may have some information as to what actually went on with Kate's mother's murder."

Beckett's badge

When Beckett quit the NYPD, fans began to speculate on what twists await Castle's beloved woman.

'Castle' fans need not worry. Marlowe has spilled that Beckett, who resigned from her post in the Season 4 finale, will soon have her badge back.

Still, Marlowe said Beckett won't have her badge yet on the Season 5 premiere.

"In the first episode she's not [back with NYPD]... but there's not a show if she's not investigating," he said.

Two fabulous grandmas in two New York-based series

Caroline Lagerfelt, who played Serena's grandmother in the teen drama "Gossip Girl", will guest star in one of the Season 5 episodes.

Ms Lagerfelt, who has proven her brilliance in playing quirky granny roles, would do great in a scene with Susan Sullivan. However, it is not know yet whether Ms Sullivan, who plays Rick Castle's mother in the series, will have an encounter with Ms Lagerfelt in the series.