Thomson, who plays Cara Lynn, spoke to TV Line about the final two episodes of the HBO series, stating that all the current storylines will be "wrapped up".
"Everything will get tied up and the series ends on a put-together note," said Thomson. "It is very shocking and outrageous. All I can really say is to expect the unexpected. It all does get wrapped up though, believe it or not."
Thomson went on to speak about Cara Lynn's relationship with her mother Nicki, played by Chloe Sevigny.
She added: "Nicki and Cara Lynn are at a breaking point right now, and this week Nicki just goes crazy. Nicki's always dramatic, but she's going to put Cara Lynn through the wringer. And the finale is going to be very good."
The final episode of Big Love will air on HBO on March 20.