What starts out as a usual homicide for Castle (Nathan Fillion) and Beckett (Stana Katic) soon grows much more ominous as the pair uncover a terrorist plot and evidence that a dirty bomb is loose somewhere in New York City. Heroes‘ Adrian Pasdar guest-stars an agent from The Department of Homeland Security, who, at least according to Castle is going after the wrong man. Castle and Beckett’s own investigation leaves them suspended, but also leads them to the bomb.
After being rescued from a frozen death by Ryan (Seamus Dever) and Esposito (Jon Huertas), with an assist from Alexis (Molly C. Quinn), the pair get back to work tracking down the bomb before it can be detonated in New York City. All of this leads, of course to Castle staring at a ticking timer and absolutely no understanding on how to diffuse the nuclear weapon.
A little different from the regular murder of the week Castle usually sticks to, but it has always been its characters and the relationships between them that has carried this show. And all of that is on stage here, including Castle and Beckett working out of his apartment, Castle’s frank discussion with his mother (Susan Sullivan) and Alexis about an impending event, and yet another tease at the possibility of the two leads getting together. And there’s plenty of tension to go around here as well.