When a carefree woman makes a youthful promise to help her best friend, who is facing the possibility of living or dying with hereditary Huntington's disease, she doesn't realize the extent and weight of her responsibility.

SYNOPSIS:

Jane and Charlotte have been raised like sisters and best friends since childhood. While the shy Jane often lives in the shadow of Charlotte's big, outgoing personality, their close bond is unbreakable. However, a dark revelation comes when Charlotte confides that her mother died from the inherited Huntington's disease - a cruel illness that could also be passed down to Charlotte, causing her entire persona to deteriorate over time.

Fearful of suffering the same terrible transformation as her mother, Charlotte makes the shocking request for Jane to promise that if she ever inherits Huntington's, Jane will mercifully end Charlotte's life.

Many years later, Jane has become a nomadic artist, traveling alone and purposely avoiding putting down roots. In contrast, Charlotte has settled into a traditional family life - she is married to Robert and they have three children, and Charlotte works as a teacher.

When Charlotte manages to track down her wandering friend Jane, she is alarmed to see Jane is still stuck in the same drifting lifestyle they used to share as free-spirited youths. Charlotte convinces the reluctant Jane to move nearby, hinting that she has an ulterior motive for wanting her oldest friend so close.

As Jane reacquaints herself with Charlotte's hectic family existence, she cannot ignore the glaring signs that her long-ago fear may be coming true. Strange outbursts, irrational behaviour, and memory lapses from Charlotte raise major red flags, though Charlotte brushes off any talk of having inherited Huntington's.

But Jane witnesses first-hand the rapidly unravelling effects on Charlotte - extreme mood swings, a breakdown that lands Robert in jail for suspected abuse, and Charlotte's crumbling relationships with her husband and eldest daughter Maryjane.

Desperate to avoid fulfilling her harrowing vow to Charlotte, Jane researches potential treatments. She finds an experimental therapy trial run by Dr. Smith that could be Charlotte's last hope - but only if she receives an official Huntington's diagnosis first.

After initial resistance, Charlotte finally agrees to get tested and meet with Dr. Smith. But in a shattering blow, they learn Charlotte's degeneration has progressed too far to qualify for the treatment trial.

Jane is finally faced with the traumatic reality of having to uphold her life-ending promise to her dying best friend. But can she actually go through with it?

In a heartrending trip to the hospital, Jane soaks in every bittersweet lucid moment with Charlotte, reminiscing about their lifelong adventures and reliving the vibrant former self of her friend. But the harsh neurological declines from Huntington's viciously return, leaving Charlotte begging Jane to mercifully end her agonizing, traumatic existence.

As much as it devastates her, Jane simply cannot bring herself to smother the withering person Charlotte has become. That's when Maryjane, Charlotte's daughter who had refused to get tested for Huntington's due to the unbearable implications, makes the courageous decision to help release her suffering mother.

Bonded forever by this agonizing act of love, Jane and Maryjane's lives become darkly intertwined through their shared weighty secret - one made even heavier by the potential Huntington's future that may still await them both.

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