Fans of Grey's Anatomy are still wondering what has become of Derek (Patrick Dempsey). In the final scene of episode 20, the answer to this question was teased when Meredith, played by Ellen Pompeo, was met at her window with flashing red and blue lights.

This moment makes viewers think that Derek might be dead, but according to the synopsis for the next episode, Derek is alive.

According to the summary for episode 21, titled "How to Save a Life," Derek did not make it to his meeting in Washington. The synopsis says "Derek witnesses a horrible car accident and springs into action," which finally confirms the reason for Derek's mysterious disappearance.

Meredith spent the entirety of last week's episode wondering where Derek could be especially after learning that there was a plane crash in Seattle.

This causes her to experience Post Traumatic Stress Disorder because of the previous plane crash involving the two doctors on the show, and made her even more anxious about her husband's disappearance.

In the promotional video clip for the new episode, Derek can be seen watching a car in front of him crash and flip over. He decides to reach out and help the victims of the car crash, telling one of the victims "I don't let people die," as she lies in the street.

The trailer ends with one of the vehicles bursting into flames. Fans wait on the edge of their seats to find out whether Derek is able to keep his promise to the car crash victims.

Tune in to next week's episode which will air on ABC at 7:00 pm Central Time, this Thursday.