'Big C' Season Finale Preview

Sex and drugs may have kept The Big C on a roll in its sublime second season, but it was a pair of pitch-perfect plots that elevated the dramedy to new heights.

The first was a beautifully symbiotic storyline, shared by Cathy (Emmy nominee Laura Linney) and cancer buddy Lee (played by Hugh Dancy) that came to an emotionally crushing conclusion in last week's penultimate episode. The second was a paternal sneak peek which elated and then destroyed Cathy's brother, Sean (the infallible John Benjamin Hickey).

Now, in tonight's season finale, those two storylines come to a head as Cathy runs Lee's marathon in his memory, and Sean acts as her mileage motivation. Well ... for a while.

Check out an exclusive sneak peek of tonight's season ender -- one that actor John Benjamin Hickey promises will leave fans with their jaws on the floor!

The Big C airs tonight at 10:30 p.m. on Showtime.