Anqi was imprisoned for manslaughter. The victim was her husband Zi Wen. There were doubts as to whether she indeed killed him. The usual suspects - her long-time good friend Ye Ning who had a child with Zi Wen, Shi Sheng who was Anqi's partner in an illicit affair and the father of Anqi's daughter, a cop who wanted to kill Anqi.
The actual solution is completely unexpected.