Since I don't know the details of 'cross her heart a novel', it could potentially be about a character facing a moral dilemma. Maybe she has to cross her heart and tell the truth in a difficult situation that affects her and those around her. It might also deal with themes of loyalty and betrayal, where the act of crossing her heart symbolizes her commitment to a certain path or person.
The novel 'cross her heart a novel' could center around a female protagonist. It might be that she has a hidden past or a deep - seated desire. The 'cross her heart' part could imply that she is bound by some unspoken oath or inner truth. This could lead her into various adventures, encounters with different characters, and self - discovery as she tries to uphold whatever it is she has promised or is committed to within herself.
I haven't read this novel specifically, so I'm not sure about the exact main plot. But generally, it might be about a woman's journey, her secrets, relationships, or some sort of personal growth. It could involve her making a solemn promise (cross her heart) that is central to the story.