The biggest twist of all might just be that Sara is the killer. Towards the end of the season, Alex discovers Sara's notebook hidden away in a wall. Her writings and scribbles detail Sara's battle with depression and suicidal thoughts. Sara also stole a tape of Sergio murdering Flor, hiding it with her friend Marifer as insurance against any possible retaliation from César or Sergio. Sara knew César was dangerous and he didn't take news of her pregnancy well, leading to her eventually becoming paranoid and suicidal.
Alex is led to believe that Sara died as a result of the parasailing accident, but that might not actually be the truth. When Alex discovers Sara's journal, he calls Elisa to let her know they've been wrong about everything. Then there are the flashbacks of a woman being choked and César shooting the gun. Did Sara ask for someone else to end her life because she couldn't bare the mental anguish and trauma she'd been through in relation to César's dirty dealings? Here's hoping Netflix gives us answers in season two.