Actress Sarah Wayne Callies bowed out of Prison Break after the second season due to contract negotiations, and in season three it’s revealed her character was executed off-screen. Her head is sent in a box to love interest Michael, and while he surely appreciated the Seven reference he was also devastated at the loss.
Sara's abrupt demise upset viewers, but it upped the stakes of the show. Sadly it was clear Prison Break was running low on ideas, with season three failing to inject new life into the story. In an attempt to appease disappointed fans it was revealed Callies would be rejoining the cast for season four, with her death being an elaborate fake-out by the villains.
The sheer ridiculousness of this twist caused many to give up on the show, and the steep downturn in ratings saw the fourth season was the last before it was cancelled. A new revival series will arrive in 2017 though.