Here's one of the "accusations" made in the Davies book.
"Next, Davies turned his attention to Darwin’s Journal of Researches, known better to modern readers as Voyage of the Beagle. Originally published in 1839, the book was reissued in a revised edition in 1845. In the interim between the two editions, Darwin had worked to develop his species theory, and the revised edition of Journal of Researches contained new interpretations of Darwin’s original observations.... Davies implied that this was a means for Darwin to establish priority by giving the impression that he was already thinking about evolution aboard the Beagle before he ever read Blyth or Matthew.
H o w e v e r . . .
The Money Quote (TMQ): "As Christians concerned with presenting the truth, creationists should avoid Davies’s conspiracy theory. Love him or hate him, Darwin was the author of his theory of evolution by natural selection."
"There is no Darwin Conspiracy"
Todd Charles Wood, Center for Origins Research and Education, Bryan College, Dayton, TN
Another view here: Did Darwin plagiarize his evolution theory? Jerry Bergman
"Good evidence now exists to show that Darwin ‘borrowed’... all or most of his ‘dear child’ from other researchers. They were not ‘his own brainchild’, nor his child, but that of others which he appropriated, evidently often without giving them proper credit."