Facebook could be spending the next few weeks responding to criticisms from investor Roger McNamee, who’s ready to go on a book tour discussing the world’s largest social network.

McNamee’s upcoming book, Zucked, is slated to be released next month. The book, which was earlier reported on by Axios, aims at discussing what it calls “the Facebook catastrophe” and why McNamee believes “Facebook’s flaws outweigh its considerable benefits.”

Throughout the book, McNamee, who was an early investor in Facebook and still holds shares in the company, discusses his early conversations with CEO Mark Zuckerberg and COO Sheryl Sandberg. In one exchange published by Axios, McNamee said that he advised Zuckerberg on not selling Facebook to Yahoo or Microsoft. Zuckerberg reportedly told him that one of those companies had already offered him $1 billion for the social network. Yahoo had indeed made the offer in 2006.

Additionally, McNamee said that he had played a role in Zuckerberg meeting Sandberg and ultimately bringing her to the company.

A Facebook spokesperson responded to McNamee’s allegations in a statement to Axios, saying that “McNamee hasn’t been involved with Facebook for a decade.” The spokesperson added that social network has “fundamentally changed how we operate to better protect the safety and security of people using Facebook.”

It’s unclear from the published excerpts exactly what McNamee has taken issue with at Facebook. But the company has clearly come under fire over the last couple of years for its dealings with Russian interference in the 2016 Presidential Election, allegations of working with a public affairs firm that targeted detractors, and more. Some have even gone so far as to call for Zuckerberg’s ouster. McNamee’s book is expected to detail many of those troubles.

Facebook did not immediately respond to a Fortune request for comment on the Zucked excerpts.