It was previously announced that Reilly's real-life daughter, Caitlin, will appear as Sean's "reel" daughter, Annie. Other GH stars to appear in the episode will be Genie Francis (Laura), Finola Hughes (Anna), Kristina Wagner (Felicia), John J. York (Mac), and Jon Lindstrom (Kevin). The episode's synopsis states that, while mourning the death of WSB agent Sean, the above parties are "pulled into a mystery" that has to do with Annie.
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Executive producer Frank Valentini said:
John Reilly was an incredible actor and a large part of the 58-plus-year legacy that is ‘GH.' This episode is meant to honor him and his contribution to the show’s rich history. With so many fan favorites returning, new and longtime viewers will enjoy it. We had a lot of fun filming and I am grateful that we were also able to include his daughter. Viewers will hopefully also enjoy one more surprise return – it is just too amazing to spoil.