Someone is about to die on the season finale of Supernatural.

Meanwhile, as producer Sera Gamble put it:

"Sam comes up with an incredibly risky Hail Mary to defeat Lucifer, which involves spending some very creepy, violent one-on-one time with the guy."

It also involves Dean getting on board with his brother's seemingly crazy plan. Watch their interaction below, courtesy of Thursday's episode, "Swan Song."

[video url="http://www.tvfanatic.com/videos/swan-song-clip/" title="Swan Song Clip"] [/video]

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