It's been a long time since I've encountered as honest of a narrator as Offred in The Handmaid's Tale by Margaret Atwood. Through the novel she would forewarn the reader when she was recreating a scene or adding in information that was she learned later. She would tell a story the way she wished it played out, but then retracting by saying, "That's not how it happened." At one point, it even took her three attempts to get the story right.
In the epilogue, we are told that the story we have been hearing was actually recorded on a series of tapes that some professors and experts had to put into logical order. This frame also adds to the honesty of a "reconstruction" of past events rather than a linear telling of what happened, where, and to whom. The professors assure us that the account is likely true based on what they know of their research on Gileadean society.
I listened to this as an audiobook, and when I got to the epilogue, I was so glad I had! Offred intended for her story to be heard, listened to by a future generation. She spoke directly at her listener towards the end of the novel, too, saying things like, "If I meet you," and "By telling you anything at all, I believe in you." Through the audible first person narration, it felt like a sincere passing on of knowledge from one person to another. It was those moments where Offred addressed the audience that finalized any doubts one could have about her reliability. She had no reason to hide anything any more. As the professors in the epilogue said, there was no way to find out anything specific about who she was or where she went after recording the tapes.