Not every episode of Castle can be one for the scrapbook. Our critic could have done without this week's installment, for example.

But "The Final Nail" has serious potential, at least based on the following ABC preview.

Jason Wiles will guest star as an old friend of Castle's... and as a murder suspect. Expect some major tension between Castle and Beckett when she continues to pursue a case against this acquaintance. Get your first look at footage from the installment now:

Matt Richenthal is the Editor in Chief of TV Fanatic. Follow him on Twitter and on Google+.