Alan Masters, who works for the city as a safety inspector is poisoned with his own water while on the phone with his cable company. Just as Lanie declares him dead, he wakes up and no one can figure out why the poison didn’t kill him.
Later, Castle takes Alan home from the hospital with a police escort. Someone has rigged Alan’s bed to electrocute him. Once again, Alan appears dead, but isn’t. Castle thinks he’s immortal because he was dealing with a chemical spill at a lab.
Alan couldn’t be bought off which may be the cause of someone wanting to kill him. Castle takes Alan out so he can go on a date with Gwen the woman he has a crush on but it doesn’t go well. When mobster Horatio Spate shows up to give Alan an ultimatum and Castle mentions Alan being a superhero, Gwen gets scared off.
Turns out Horatio has ties to a rival gang, the Triads. They are both investing in synthetic heroin which can be made in a lab. Alan saw large amounts of it at a lab. When he runs to the lab to warn Gwen to be careful, it turns out that she is Horatio’s girlfriend and she shoots Alan in the head.
Alan wakes up from his head wound. The small caliber bullet didn’t penetrate his skull. Lanie is amazed and the two decided to spend some time together and see what other superpowers he may have.
Vikram finds photos of Caleb Brown in Los Angeles the same time that LokSat was there but using the alias Peter McCafferty. Hin inspection of the video footage tips off Caleb who tries to warn Beckett off the investigation. Beckett asks him to join forces or she’ll expose him and LokSat will kill him anyway.
Caleb breaks into Castle’s loft. He gives Beckett the device that LokSat uses to contact him once per month and wishes her luck in tracking them down.