Stairway to Heaven
performed by Led Zeppelin

Well there's a light in your eye that keeps shining Like a star that can't wait for the night I hate to think I've been blinded baby Why can't I see you tonight? And the warmth of your smile starts a-burnin' And the thrill of your touch gives me fright And I'm shaking so much, really yearning Why don't you show up, make it all right? Yeah, it's all right. And if you promised you'd love so completely and you said you would always be true You swore that you would never leave me, baby: What ever happened to you? And you thought it was only in movies As you wish all your dreams would come true It ain't the first time believe me, baby I'm standin' here feeling blue Yeah I'm blue Now I will stand in the rain on the corner I'll watch the people go shuffling downtown Another ten minutes no longer And then I'm turning around The clock on the wall's moving slower My heart it sinks to the ground And the storm that I thought would blow over Clouds the light of the love that I found Now my body is starting to quiver And the palms of my hands getting wet I've got no reason to doubt you baby, It's all a terrible mess I'll run in the rain till I'm breathless When I'm breathless I'll run till I drop, hey The thoughts of a fool's kind of careless I'm just a fool waiting on the wrong block, oh yeah Light of the love that I found...

Izzie is still struggling with Denny as he is constantly reminding her "He is there for her". Izzie has an emotional blow out with Denny and soon understands what he is trying to tell her. She finally comes to the realization that Denny is not here "for her" in the emotional sense, which leaves Izzie reeling when she soon discovers that she is sick.

When a massive attack is unleashed on the remaining angels, Castiel is shocked to learn that it was ordered by one of his followers, while Dean- who continues to succumb to the influence of the Mark of Cain- learns that the attack is part of a conspiracy involving the Winchesters' old 'ally' Tessa the Reaper.