"Reign" season 4 will be coming with a few surprise additions despite the fact that its premiere has been pushed back. Now that the show is in production, a report from Crossmap states that two actors have been added to the cast and both will be playing husbands to Mary (Adelaide Kane). 

According to the report, Adam Croasdell has been cast as Mary's third husband, the Earl of Bothwell. This doesn't mean the show is going to skip out on her second husband, the ill-fated Lord Darnley. The report confirms that actor Will Kemp will be joining the show as Lord Darnley, although he is likely only going to appear for an episode or two.

The report continues to explain that in the real history of events, Lord Darnley was only married to Mary for a year as he was murdered in an explosion while Mary was away and this is likely going to happen on the show. The real-life Lord Darnley was known for being extremely violent and this may have led to his demise.

Due to his death, it is expected that Bothwell will come in to aid her in her time of grief. He is described as a "warm-hearted bad boy" and that his charms will eventually win her over. Their marriage will later be the cause of contrition and many believed that Bothwell and Mary had schemed Lord Darnley's murder together.

However, it is not stated that Mary will have a son with Lord Darnley. In real life, Mary became pregnant during the time Lord Darnley had been forcing her to give him the Crown Matrimonial, which would name him successor in case Mary died. She later gave birth to their son, James, who would later succeed the throne when she was forced to abdicate and flee. 

"Reign" season 4 premieres in late 2017.