Michael Fassbender and Alicia Vikander star in The Light Between Oceans, based on the acclaimed novel by M.L. Stedman. [Photo/Agencies]

What's a better bet than a Hollywood weepie based on a best-selling book? When the stars fall in love in real life while filming it.

That's the draw of The Light Between Oceans, a heart-wrenching tale based on M.L. Stedman's 2013 novel of the same name that stars Oscar-winner Alicia Vikander and Michael Fassbender. It opens in US theaters on Friday.

The story, set in Australia in the 1920s, is the tragic tale of a lighthouse keeper (Fassbender) and his wife (Vikander), who have suffered two miscarriages when a baby in a boat washes ashore their remote island. They decide to raise the child as their own, until they meet the child's real mother years later.

Sweden's Vikander, 27, one of the most sought-after young actresses even before winning an Oscar in February for her supporting role in The Danish Girl, had briefly met Fassbender a year before filming on the movie began in New Zealand in late 2014.

"We met each other on the dance floor at the Toronto Film Festival and BAFTAs－he's a good dancer," Vikander says.

"But we hadn't really ... we met properly in Wellington in the rehearsals for the first time," adds Fassbender, 39.

Michael Fassbender and Alicia Vikander star in The Light Between Oceans, based on the acclaimed novel by M.L. Stedman. [Photo/Agencies]

Director Derek Cianfrance then asked the pair to live together in a remote lighthouse for a month during filming, and by the end of 2014 news broke that they were dating.

Vikander says she cried when she first read the script for the movie, and says filming such emotional scenes was often exhausting.

"I was in tears the first time I read it and it's because it feels so human ... and it feels like it's about real people and about real drama," she says.

"It helps I had admired Michael as an actor since I saw his first films like Hunger and Fish Tank. It's like you see a very natural being for each character that I think he's done, but also getting to meet him you understand how much work gets put into it in preparation."

Both Fassbender, the star of Steve Jobs, and Vikander, say they had a good feeling during filming about how the movie would turn out.

"It seemed like we had good ingredients. And then it all depends on whether audiences take to it or not. That's really something you can never tell," he says.

Related:

China's Bourne is coming

A Korean group is pushing new cinema-viewing experience