"Ordinary, said Aunt Lydia, is what you are used to. This may not seem ordinary to you now, but after a time it will. It will become ordinary."
Offred is a handmaid, one of the most important jobs in the Republic of Gilead. She's recently been assigned to a Commander and his wife to provide a child. In this distopian future, very few women are able to conceive and bear children and so, after a military coup and restructering of society, fertile women are enslaved and passed around to continue the new heirarchy. Offred is only one of these women, caught in the middle of a regime change, still able to remember her old life, unsure of her future.
The story is told as a recollection of Offred's, leaving much of her backstory to the imagination of the reader. We don't get a detailed description of Offred but this lends itself to the story. Handmaids have their individuality trained out of them but Offred spends the whole book trying to hang onto hers.
I think if anyone either than Atwood had written the book it would have collapsed on itself or gotten lost in the plot. This isn't an action-filled book. Much of the conflict comes from internal paranoia on Offred's part, wondering if or when she's going to be caught. The suspense comes from the slow but taut reveal of the history of Gilead, without a glut of exposition to bog down the book.
The ending is abrupt and ambiguous, leaving Offred's fate in the hands of the readers but it only feels right that Atwood should leave us unsure of the end. After all, the most disturbing part of this book is how unbelievable it is and yet she describes, step by step how entirely plausible the creation Gilead and handmaid's are. Why shouldn't the reader be left feeling uncomfortable about the circumstances of the book? The distopian view of the novel gives readers something to think about.