Shailene Woodley discusses 'Adrift' and that shocking, true twist (spoilers!)

Spoiler alert! The following discusses the big reveal of the adventure drama Adrift. Stop reading now if you haven't seen it and don't want to know.

Adrift faithfully tells the true story of Tami Oldham, whose romantic sailboat trip with fiancé Richard Sharp in 1983 turned into a survival story when they were hit by a hurricane.

The film depicts Oldham (played by Shailene Woodley) interacting with the wounded Sharp (Sam Claflin) throughout much of her 41-day ordeal at sea. 

But before you can say "Hollywood ending," Adrift reveals that Sharp isn't alive, but a vivid part of Oldham's imagination.

More:Shailene Woodley goes 'Adrift' and talks seasickness, naked meditation

Sharp was swept to his death at sea during the hurricane, just as Oldham described in her 1998 account Red Sky in Mourning: A True Story of Love, Loss and Survival at Sea.

Woodley calls keeping Sharp physically onboard in Adrift — which also features flashbacks to happy days before the storm — "a unique approach" to telling Oldham's story. 

"In the book, Tami describes Richard's voice as being her guide and helping her survive," says Woodley, adding that it was vital to "honor Tami's story."

"When you have a story as dynamic and as profound as this one, you want to leave it as authentic as possible and it will elicit the shock factor," says Woodley. "This was 23-year-old woman who survived alone for 41 days at sea."

His presence emphasized how the power of their love propelled Oldham to survive.

"The beauty of this is, yes, it’s a survival story. But really, it’s a love story," Woodley says. "That’s what we hope to translate in our movie. The true love they shared became a source of will for her."

In Red Sky in Mourning, Oldham describes coming to from her head injuries after the storm and realizing instantly that Sharp had perished.

"I know in a blinding flash he's gone overboard," Oldham writes. "Snatched by the boiling cauldron of the ocean, whipped to a frenzy by the hurricane. When I realized he wasn't there, I wanted to die."

More:Here's why 'Adrift' heartthrob Sam Claflin looks so fierce

Director Baltasar Kormákur said he used dramatic license to show Woodley's Oldham finding her love clinging to a lifeboat. But Sharp's injuries prevent him from aiding Oldham's survival in any way other than encouragement.

"That was very important to me. He actually does nothing. She does it all herself," says Kormákur. "Tami uses him as an emotional kind of counterbalance."

Having Claflin's Sharp remain in the movie also allows for dialogue to explain what's happening at sea and even provide moments of levity. But Oldham starts to realize that his presence is in her head.

"And you compare it to the five stages of grief. You go from delusion and the last one is acceptance," says Kormákur. "That’s part of the journey, you see she’s grieving."

Oldham, an adviser on the film, was pleased with the way her story was handled.

"It just brought me right back on that boat. So many memories I have stuffed back in my subconscious just came flooding forward," she says.