'Reign' season 4 spoilers: Mary's new husband a killer who forced her to marriage?

Mary (Adelaide Kane) will once again find love in "Reign" season 4, but if the reports are to be believed, her journey to marriage will be difficult and life-threatening at some point.
It has been announced that Mary will first marry Lord Darnley (to be played by Will Kemp). The two have a child but the romance is cut short when Darnley was murdered a year into the marriage.
The killer is presumed to be the man that Mary will also eventually marry but not out of love—Bothwell, who will also be introduced in "Reign" season 4 by actor Adam Croasdell.
In real life, Bothwell is one of the people suspected to be responsible for killing Mary's second husband. He also reportedly kidnapped the Queen and threatened to kill her if she did not agree to marry him.
However, it remains a mystery if Mary was forced into marriage by Bothwell although many people at that time believed she was. This led to Bothwell fleeing and completely leaving Mary.
It is unknown if this will all be depicted in "Reign" season 4 as Croasdell and Kemp are only signed for four episodes although going beyond that is up to them.
Either way, fans can expect Mary once again go through hell and back in "Reign" season 4 in the name of love and her country.
The previous season was heartbreaking as it marked the loss of Francis (Toby Regbo) and it appears that Mary won't get a break in "Reign" season 4.
Filming for the new season of the historical drama is underway. The series, however, will not be back until next year.
It is being said that "Reign" season 4 will be the show's last due to the declining ratings and viewership. This would mean that the new season could very well mark her return to Scotland.