The theme of the book is that the life is very unpredictable even when it seems to be the safest
Step-by-step explanation:
The story of the book Tall grass revolves around a 13 year old girl Rennie strourd and her family.Immediately after the Pearl Harbor incident , the U.S. government shifted all the Japanese residents to the West Coast and shipped them off to "internment camps" for the duration of the war. One of such camps is Tallgrass.
During the world war II , Rennie has witnessed a murder, and had two of her best friends raped, and is trying to cope with a sick mother(who is a heart patient) and a brother in a German POW camp. Rennie very soon discovers the bitter truth of life (i.e. life is all about betrayal, lies and the keeping of secrets)
This is the reason why Rennie wants the war to end