A former Uber engineer has published an explosive account of sexism and power struggles in the workplace, with allegations beginning from her very first official day with the company. The engineer, Susan Fowler (who left Uber in December and now works for Stripe), posted the account to her blog on Sunday, calling it a “strange, fascinating, and slightly horrifying story.” It is indeed horrifying.

Sexism is a well-documented problem in Silicon Valley, but the particulars of Fowler’s account are astounding. She says problems began on day one, when her manager accosted her with details of his sex life:

In my first official day rotating on the team, my new manager sent me a string of messages over company chat. He was in an open relationship, he said, and his girlfriend was having an easy time finding new partners but he wasn't. He was trying to stay out of trouble at work, he said, but he couldn't help getting in trouble, because he was looking for women to have sex with. It was clear that he was trying to get me to have sex with him, and it was so clearly out of line that I immediately took screenshots of these chat messages and reported him to HR.

Fowler was pressured to remain under a manager who sexually harassed her, according to her account. She says HR responded by saying the company “wouldn’t feel comfortable” giving him more than a warning. She says she was then given a choice to leave her team, or continue doing her work — with the understanding it could result in a bad performance review from the manager who harassed her.

From there, Fowler’s journey only gets bleaker. She describes a “Game of Thrones political war” among upper management in the engineering department, with managers openly trying to sabotage and conquer each other:

It seemed like every manager was fighting their peers and attempting to undermine their direct supervisor so that they could have their direct supervisor's job. No attempts were made by these managers to hide what they were doing: they boasted about it in meetings, told their direct reports about it, and the like. We all lived under fear that our teams would be dissolved, there would be another re-org, and we'd have to start on yet another new project with an impossible deadline. It was an organization in complete, unrelenting chaos.

Her account of her time at the company also includes efforts by her managers to undermine her sense of reality and accomplishment. She says glowing performance reviews were later altered to justify holding her back from promotion, and keep her from transferring to other parts of the organization.

Remarkably, Fowler’s account transpired only over the course of a year at Uber, during which she felt she had to keep records of mistreatment and improper behavior. Even keeping records and making complaints to HR got her in trouble. Her own HR department tried to squash her protest for decent treatment, allegedly suggesting she was the “common theme” in her complaints, and that “it was unprofessional to report things via email to HR.” (Telling women not to complain is a hallmark of sexist organizations.) In a meeting just before she left the company, she says her manager told her she was “on very thin ice” for reporting his manager to HR, and threatened to fire her in retaliation.

In a statement emailed to The Verge, Uber CEO Travis Kalanick said the company would “conduct an urgent investigation” into the allegations, and promised to fire anyone who “behaves this way or thinks this is OK.” Here is Kalanick’s full statement:

I have just read Susan Fowler's blog. What she describes is abhorrent and against everything Uber stands for and believes in. It's the first time this has come to my attention so I have instructed Liane Hornsey our new Chief Human Resources Officer to conduct an urgent investigation into these allegations. We seek to make Uber a just workplace and there can be absolutely no place for this kind of behavior at Uber -- and anyone who behaves this way or thinks this is OK will be fired.

Uber has had plenty of high-profile controversy in the past, including problems with high-ranking executives. In 2014, Uber vice president Emil Michael threatened Pando Daily editor-in-chief Sarah Lacy with a smear campaign. Kalanick later said those remarks “showed a lack of leadership, a lack of humanity, and a departure from our values and ideals.”

In the most bizarre part of the account, Fowler describes how a senior manager promised to order leather jackets for all of the site reliability engineers — but at the last minute informed the women on the team that they would not be receiving any, because there were not enough women to justify the expense. (She says there were only six women.) Fowler says more than 120 men received their jackets, and that the manager said it wouldn’t be fair to order women’s jackets unless they could find a way to receive a bulk discount like the men.

Fowler says that when she joined Uber, women represented 25 percent of the organization she worked in. On her last day, she says that number was down to 3 percent.

Update February 19th, 7:32PM ET: Story updated to include comment from Uber CEO Travis Kalanick.