Ep 3. Clear & Present Danger

In Castle season 7 episode 3, entitled "Clear & Present Danger," the NYPD tackles a unique case when the body of a doctor is found to contain a rare and deadly virus. Castle and Beckett must work with the CDC to prevent the virus from spreading while also tracking down the killer. Meanwhile, Castle struggles with the possibility of being separated from his daughter, Alexis, as she prepares to leave for college.

The episode begins with Dr. Isaac Heller collapsing on the street and dying within minutes. When his body is brought to the morgue, medical examiner Lanie Parish discovers that he was infected with a fatal virus that is extremely rare and difficult to obtain. The CDC is called in to help contain the virus, but they reveal that there is no known cure.

Castle and Beckett join forces with the CDC to track down anyone who may have come in contact with the virus. They discover that the virus was originally stolen from a lab where Dr. Heller worked years ago. Castle and Beckett question Dr. Heller's former colleagues, but they deny any involvement in the theft. However, when they find out that one of the colleagues had a motive to steal the virus, they decide to investigate further.

As the investigation continues, Beckett begins to show symptoms of the virus, causing concern for the entire team. The CDC insists on isolating her to prevent a potential outbreak. Meanwhile, Castle begins to worry about Alexis, who is set to depart for college soon. He struggles with the realization that he will be left alone at home without his daughter.

Through their investigation, Castle and Beckett discover that the virus was stolen by Dr. Heller's former assistant, who had been fired from the lab years ago. The assistant reveals that he stole the virus out of revenge, but had no intention of harming anyone. He hands over the virus, allowing the CDC to develop a cure.

Eventually, Beckett is cleared of the virus and rejoins the team to solve the case. With the virus contained and a cure in development, the team is able to close the case and return to their normal lives.

Overall, "Clear & Present Danger" is a thrilling episode that explores both the dangers of bioterrorism and the importance of family. Through excellent performances from the cast and gripping storytelling, it keeps viewers on the edge of their seats until the very end.