One Step Too Far

"We're trained to be vigilant. To chase down the problem. To ask all the right questions. To find the root cause, until we know exactly what it is. And we can confront it. It takes an extreme amount of caution, or we can overstep ourselves. We can create problems, where none exist. Our intentions are always pure, we always want to do what's right. But we also have the drive to push boundaries, so we're in danger of taking things too far. We're told to do no harm, while we're trained to cut you open with a knife. So, we do things, when we should have left well enough alone. Because it's hard to admit when there's no problem to treat. To let it alone, before we make it so much worse. Before we cause terrible damage."

- Meredith Grey

 is the seventeenth episode of the eighth season and the 165th overall episode of Grey's Anatomy.

Short Summary
Derek encourages a hesitant Meredith to work with him again in neurology; Jackson’s mother, Catherine Avery, returns to Seattle Grace with a urology fellow and develops an interest in Richard; and Cristina becomes increasingly suspicious of Owen’s every move. Meanwhile, Alex tries to deny the fact that Morgan may be falling for him.

Full Summary
Episode in detail.

Main Cast

 * Ellen Pompeo as Dr. Meredith Grey
 * Sandra Oh as Dr. Cristina Yang
 * Justin Chambers as Dr. Alex Karev
 * Chandra Wilson as Dr. Miranda Bailey
 * James Pickens, Jr. as Dr. Richard Webber
 * Sara Ramírez as Dr. Callie Torres
 * Eric Dane as Dr. Mark Sloan
 * Chyler Leigh as Dr. Lexie Grey
 * Kevin McKidd as Dr. Owen Hunt
 * Jessica Capshaw as Dr. Arizona Robbins
 * Kim Raver as Dr. Teddy Altman
 * Sarah Drew as Dr. April Kepner
 * Jesse Williams as Dr. Jackson Avery
 * Patrick Dempsey as Dr. Derek Shepherd

Guest Stars

 * Debbie Allen as Dr. Catherine Avery
 * Summer Glau as Emily Kovach
 * Amanda Fuller as Dr. Morgan Peterson
 * James Avery as Sam
 * Rebecca Hazlewood as Dr. Mara Keaton

Co-Starring

 * Ginny McMath as Irene
 * Chelsea Harris as Lori
 * Charles Emmett as Mr. Bosson
 * Rosalyn Sidewater as Mrs. Bosson
 * Payton Silver as Dr. Knox
 * Teresa Huang as O.R. Nurse

Notes and Trivia
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 * This episode's title originated from the song One Step Too Far, originally sung by Faithless.
 * This episode scored 9.62 million viewers.