ABC bumps 'Castle' episode in light of Boston Marathon explosions Actor Nathan Fillion attends the People's Choice Awards 2013 at Nokia Theatre L.A. Live in Los Angeles on January 9, 2013. LOS ANGELES, April 18 (UPI) -- Monday's bomb-themed episode of the New York-set cop drama "Castle" has been replaced following the explosions at the Boston Marathon, EW.com said. The episode is being swapped with the one that scheduled to air April 29. The ABC show stars Nathan Fillion as a mystery novelist who solves crimes alongside a beautiful New York City homicide detective, played by Stana Katic. Three people were killed and more than 175 injured in twin explosions at the Boston Marathon this week.