Caroline Lagerfelt Caroline Lagerfelt

Caroline Lagerfelt, who played Serena's (now-deceased) grandmother on Gossip Girl, has booked a guest role on Castle for the ABC drama's fifth season, TV Line reports.

During a case investigation, Castle (Nathan Fillion) and Beckett (Stana Katic) will encounter Lagerfelt's character, a wealthy socialite named Angelica Henley who employed the victim, according to TV Line.

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Castle premieres Monday, Sept. 24 at 10/9c. Lagerfelt's episode is scheduled to air in October.