Season 5 is a pivotal one for the riveting Grey's Anatomy. The doctors at Seattle Grace Hospital bloom and show new layers, the drama meets and exceeds that of previous seasons, and the show marks an important milestone--its 100th episode--with developments that, as with all the great Grey's episodes, brim with belly laughs and moving tears.

The season gets off to a slow start, with perhaps a bit more relationship angst than even diehard fans would prefer. Meredith (Ellen Pompeo) and Derek "McDreamy" (Patrick Dempsey) start out with the familiar push-pull of their love affair--but a resolution, at last, is in their future. Callie (the excellent, and newly glamorous, Sara Ramirez) wrestles with her sexual orientation. Cristina (Sandra Oh, never better) is still picking up the pieces from her ruined engagement to the departed Burke (Isaiah Washington). To help her, or maybe to throw her for another loop, the series introduces the gruff, macho military doc, Owen (one of TV's sexiest hunks, Kevin McKidd).

Yet series creator and still active writer Shonda Rhimes unveils story arcs about midway through the season which have the surgeons' operating room dramas intersecting with the characters' private lives--with waves of heartbreaking results. Fans may take issue with "Dead Denny" (Jeffrey Dean Morgan) and his endless visitations--complete with sex--with Izzie (Katherine Heigl)--but as the season builds, Izzie's mystery illness, and her deep love for Alex (Justin Chambers) are treated with delicacy and respect, and Denny's character both reacts and ultimately supports. There's a wedding--a fairy-tale one--celebrating the show's 100th episode, and the love of the characters, and the pain they've overcome to get there--are equal parts of the very human, very lovely, result. The season finale is among the show's best ever, with the fate of two beloved characters, George (T.R. Knight) and Izzie, left unknown and laden with sorrow. --A.T. Hurley