"Outlander" is currently in the middle of filming its third season, and fans are already scouring the internet for any news and spoilers for the upcoming installment. To ease the pain of those who are suffering from Droughtlander, important casting news has been recently announced, and one of the new arrivals will be a game changer in the series.

According to Deadline, newcomers Hannah James and Tanya Reynolds will be playing the Dunsany sisters, Geneva and Isobel, respectively. The two are the children of Lord and Lady Dunsany, who live in the Helwater estate. Geneva is described as being very beautiful, headstrong, petulant, and spoiled, while Isobel is said to be the direct opposite and is warm, friendly and genuine.

In Diana Gabaldon's third "Outlander" novel titled "Voyager," Jamie (Sam Heughan) serves the rest of his sentence while on parole at the Helwater estate as a groom, and there, Geneva blackmails him into sleeping with her.

Because of this new casting development, viewers can expect that when the show returns, Jamie will be keeping a major secret from Claire (Caitriona Balfe). In the book, Geneva and Jamie's one night together results to her getting pregnant with his son and the boy is named William. Before she died, Geneva managed to make other people believe that the boy was fathered by her husband, the Earl of Ellesmere, but when William grows up and starts to resemble Jamie, the Scot decides to leave Helwater for his son's sake.

After Claire goes back in time to reunite with Jamie, he is overjoyed to be with her, yet terrified of what will happen once he tells her about his secret. In Gabaldon's third novel, it takes some time before Claire learns about William's existence, and Jamie's secret is revealed to her by John Grey, who will be played by David Berry in the TV series. John knows about William because he married Isobel, and the two ended up raising William as their son.

It has not been confirmed if Starz will follow this chain of events for season 3 of the hit show, but it's likely that the TV series will stay true to its source material, with some twists thrown in for good measure.

"Outlander" season 3 premieres in 2017 on Starz.