Abby departed for the Emerald Isle in the season 1 finale of 9-1-1 following an emotional goodbye with Buck, which ended Britton's time as a main cast member and left Abby and Buck's relationship in limbo. Connie Britton and her character Abby left 9-1-1 after Britton's one-year deal with the series came to an end.

Why did Abby leave 911?

Unwilling to carry on with her profession, Abby decides to reflect on her life and take the time to fulfill her mother's wish of traveling to Ireland. With a determination to live her own life, Abby bids a tearful goodbye to Buck and embarks on her own journey.

What episode does Abbie come back 911?

She leaves for Ireland in the episode "A Whole New You" and is gone until she finally returns in the season 3 episode "Powerless" when she is involved in a serious train accident that causes the train to derail.