So much for keeping things ami­cable! On September 20, Sophie Turner filed a bombshell lawsuit against estranged husband Joe Jonas for the “immediate return” of their two young daughters, Wil­la, 3, and D., 14 months, to England.

According to court docs, the “Suck­er” singer, 34, is in possession of their children’s passports and is refusing to hand them over. “Sophie felt she had no other choice but to sue and get the court involved,” a source exclusively tells Life & Style. In her filing, the Game of Thrones star, 27, alleges that she and Joe decided to put down permanent roots in the U.K. while celebrating Christ­mas with her family in England last year. They found a “beautiful coun­try property” in Henley on Thames and put their Miami mansion on the market. But when their marriage began to fall apart, so did plans for the big move.

Sophie says that she and Joe got into an argument on August 15, and three weeks later, she found out through the media that he had filed for divorce. When Sophie met up with Joe on September 17 to collect the kids, the boybander refused to allow the girls to return home to England with her. The insider tells Life & Style: “Sophie doesn’t even know who Joe is anymore.”