BITTER FREEDOM by Jafa Wallach; Hermitage Publishers; 188 pages; $15.95.

With the inevitable passage of time, memoirs of Holocaust survivors become more and more invaluable and precious - for, before too much longer, they will be the only means of transmitting the truth about those catastrophic years to future generations. So, like other works of its genre, this memoir deserves an honored place among the stories of death and destruction - and, in a few cases, survival - that have come out of that era.

And, in its own way, it is a unique story. For the writer, along with her husband and two of her brothers, spent almost two years literally entombed in a tiny hole in the ground, less than six feet long and five feet wide, and not high enough for an adult to stand in. They had dug the hole themselves, its walls were earth, and they shared  it with an army of rats and other rodents. They did, however, have one vital source of help - a truly righteous gentile who risked his livelihood and indeed his life to sustain the little Jewish family living under the floor of his workshop.

She wrote it for her daughter, Rena Bernstein, herself a survivor who underwent a  different but similarly harrowing ordeal. Apparently, she had no intention of having it published, but recently Rena thought otherwise, so it finally was given to the world last year.  The prose is straightforward and easily readable. The only possible sticking point comes in figuring out the relationships of the various characters who play roles in the real-life drama. Most of them were members of Jafa's or her husband's extended families. And there is one other perplexing note, the title - Obviously, their years of extreme peril were bitter, but could that also be said of their freedom?

In many ways, the real hero of this story of survival is Josef Zwornaz, better known as Jozio, the aforementioned gentile whose devotion to his fellow human beings was truly extraordinary. A mechanic, he owned a small workshop where, among other jobs, he repaired the nazis' vehicles. Posing as an unprepossessing, unsophisticated workman, he actually aided the Polish underground in the various ways, in addition to his specific goal of supplying theWallachs and their relatives with as much food as he could get his hands on, and bolstering their morale with "good news." even if had to invent it. His story is more than inspiring - he was one of only a very few Poles willing to do what he did. And he ultimately was rewarded with a medal from Yad Vashem, Israel's Center for Holocaust Remembrance. He words on receiving the medal encapsulate his viewpoint: "It's better to get a medal for saving one person, than for killing thousands."

Daughter Rena has added her afterword to her mother's account - she was little more than a toddler when she was spirited off to hide in a forest cabin, far from any real human contact, and her story also is a poignant one. There is a gallery of photos and finally, a brief appendix by Jafa's sister, Helena, depicting her own story of survival.