As ABC's Castle launches into November sweeps, the series will be featuring a very serious episode while also including what is sure to be a humorous one.

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Castle fans who watched the promo for the next episode of the series saw that Castle (Nathan Fillion) and Beckett (Stana Katic) may finally be getting married. Moving forward in the series, there will be a relatively light-hearted episode followed by a dark episode, based on new plot synopses from ABC.

After The Time of Our Lives, which airs on Monday, Nov. 10, Castle will be airing an episode called Once Upon A Time In the West.

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"When Castle and Beckett learn that a murder victim may have been poisoned at an Old West-style resort; they visit the resort -- posing as newlyweds -- to uncover the truth," the plot synopsis for the episode reads. This episode airs on Monday, Nov. 17. It is fitting that Castle and Beckett will be posing as newlyweds considering the previous episode's events.

The next episode is titled Kill Switch and features a dangerous hostage situation.

When subway passengers, including Detective Esposito [Jon Huertas], are taken hostage by a mysterious gunman, Castle, Beckett and the team must uncover the gunman's agenda before it's too late," the synopsis reads. This episode will air Monday, Nov. 24. This is certainly the type of episode fitting for November sweeps.

Castle airs Mondays at 10 p.m. ET/PT on ABC.

Watch the promo for the next episode of Castle here:

Tags: Castle television ABC