One bad season is often enough to kill off a hit TV show. Once the bad reviews start trickling in and the viewers are tuning out in their thousands, network executives have tough decisions to make. Do they swing the axe now as a means of damage limitation, or give the series a chance to redeem itself with a risky renewal order?
History tells us that once the rot has set in, there's usually no going back. The Simpsons has been on a downward trajectory in quality terms since the turn of the millennium and, while Fox is unlikely to kill off the series that put it on the sitcom map, other shows with similarly inconsistent output haven't been so fortunate.
But every once in a while, broadcasters take a punt on a down-on-its-luck show and are rewarded for their faith. The writers return to the drawing board having learned from their mistakes and bring the series back from the brink.
Flagging TV shows have bounced back from terrible seasons and returned to form in many creative ways, from throwing out their format, to refreshing the cast, and here are some of the most ingenious ways they've pulled it off.