Mountains of the Moon — Marjorie Curtis

After years of patient waiting, Penny flies to Brazil to visit her father only to learn when she arrives at Macapa that he has died. Disregarding her friends' warnings, she sets off alone to find the Rubber Settlement where he worked, deep in the dense jungle country, close to the dreaded Purus River. Finding herself stranded in a town on the Amazon, she has to rely on two plantation men to take her upstream to her destination. One is pleasant and unassuming and the other is cynical and strongly disapproves of women being in the tropics.

Obstinately, she refuses to be discouraged for she has good reason to endure danger and hardship which was eventually to lead her safely to happiness.