The third season ended with Sofia Helin's Norén, who had been forced out of her Malmö police job, agreeing to help Danish actor Thure Lindhardt's character Henrik Sabroe find his missing children.
The fourth season picks up two years after the third one left off, and much has happened since then.
“Have you seen Saga lately?” a Swedish voice (we think it sounds like it could be the Malmö police chief, but this has not been confirmed) asks Sabroe. “She doesn't always want to see me,” he replies.
“A lot has happened in Saga's life. She is somewhere else,” Rosenfeldt told Expressen.
“Something has happened that means she is not always keen to meet Henrik.”
He also said the upcoming season will reveal more about the characters' personal lives, but as always on The Bridge there will also be a criminal case. One scene of the trailer shows a woman being stoned.
“It is a Danish woman who has a high-profile job, who is abducted, partly buried and stoned to death under the Öresund Bridge, on Peberholm (an island between Sweden and Denmark, where the bridge becomes a tunnel on the Danish side) That's what kicks this season off,” said Rosenfeldt.
Asked to reveal something not shown in the trailer, he said: “You don't actually get to see that much in the trailer. For the first time we spend more time outside of Copenhagen and Malmö – now we've got a small village outside of Malmö which will be a major location. So we're not completely urban.”
“In England they're writing a lot about this Nordic Noir wave being over, but I hope that season four of The Bridge will show that no, it is not,” added Rosenfeldt.
“And I acually think, or I know because I've seen it several times in different versions: the final episode is amazing.”