When the Levee Breaks
| Episode Number | 21 |
|---|---|
| Season | 4 |
| Aired | 2009-05-07 |
| Overview | Dean and Bobby have something frightening locked in Bobby's panic room: Sam, contaminated by demon blood. But as the apocalypse draws nearer, Bobby wants to free Sam to battle on their side. |
| Runtime | 43 minutes |
| Absolute Number | 81 |
| Finale Type |