Liz was the smart, bossy big sister; Maggie was the “good” sister, tiny and quick as a hummingbird. Loving but competitive and mutually judgmental, the girls grew up to live very different lives: Maggie married her childhood sweetheart, stayed in rural Vermont, trained as a nurse-practitioner; Liz married a doctor, moved across the country, got divorced, wrote books.

The sisters were 54 and 52, respectively, when Maggie was diagnosed with Stage 4 mantle cell lymphoma, a cancer so aggressive that doctors insisted on beginning treatment (chemotherapy, radiation, isolation) the afternoon of her diagnosis. Fortunately, it worked: The cancer went into remission and stayed that way for seven years.

And then it came back, more deadly than before.

Marrow: A Love Story” is Elizabeth Lesser’s account of how she was given the great “gift” of being a perfect match for the bone marrow transplant that, once the cancer reappeared, offered the only hope for saving Maggie’s life.

As the co-founder of a holistic health and spirituality center, Liz was open to the idea that a strong mind-body connection between the sisters would give her transplanted bone marrow cells their best chance of making a successful transition to Maggie’s body. They embarked on what she calls a “soul marrow transplant.”

A clear and graceful writer, Liz is adept at describing both the transplant process — it’s not surgical; rather, stem cells were removed from Liz’s blood through an IV line and donated to Maggie — and the emotional and psychological process of sharing blood, of becoming a sort of joint entity whom she calls “Maggie-Liz.” She brings anecdotes from history, mythology and philosophy to bear on an essentially tragic story.

Maggie is no saint — she has no patience for anyone “without a death sentence”; Liz remains bossy, wanting to be in charge of everything. After a year, it becomes clear the transplant has failed. Final treatments are painful, frustrating, enraging.

Readers may recall “My Sister’s Keeper,” the 2004 Jodi Picoult novel, later made into a movie, about a teenager who refuses to donate a kidney to possibly save her dying sister. That was a tear-jerker — but this is far more so, a real-life story with no happy ending but many joyful moments.

When Maggie realizes with embarrassment that she has come to the extremely predictable insight that “the more I let myself be me, the better things got between me and other people,” it reminds you that cliches become cliches because they are true. “This is how to live,” the sisters’ therapist says emphatically. “You don’t have to die to live like this.”