Mark talks with Callie about love. Seriously. Bailey heads a risky surgery – even by Seattle Grace standards. Derek gets sole credit for a tumor study he and Mer did.

Meredith freaks when Derek discovers her mother’s diary, Callie preps for a date with Erica, and Cristina stumbles into a new part of the hospital.

In case the title didn’t give it away, Seattle Grace is hit by a flood in this episode. Or more accurately, a plumbing fiasco.

Meredith and Derek soon discover that ‘happily ever after’ isn’t that easy, a military doctor, Dr. Owen Hunt, catches Cristina’s eye, an…