breaking newsLindsay Lohan was an utter disaster on the set of the movie "The Canyons" ... this according to a writer embedded with the production, who says he saw a seemingly drunk LiLo get into her car and drive off the set after a boozing session.
The man who wrote article is Stephen Rodrick -- who says he was allowed to chronicle the project from start to finish.
According to Rodrick, Lohan was a mess who was initially fired after blowing off two days of filming. Rodrick says Lohan showed up to the director's hotel room, pounded on the door while hysterically crying and begging for her job back.
Rodrick says Lohan stayed in the hallway sobbing for 90 minutes before finally leaving.
Eventually, she was hired back to the production -- and things got worse ... with Lohan constantly criticizing producers and her co-stars.
But the most concerning part, Rodrick says Lohan had been drinking before a scene in which she would be simulating a 4-way sex scene with some real-life porn actors.
After the scene, producers offered Lindsay a hired car to drive her home ... but she refused ... and drove off in her Porsche. Rodrick says producers "all hoped they would still have a lead actress in the morning."
In the article, Rodrick says Lohan also freaked out before a sex scene in which she was supposed to get naked ... and locked herself in a closet. Rodrick says the director had to beg her to do the scene ... and eventually stripped naked himself to show her it was no big deal.
The gimmick worked -- Lohan eventually dropped her robe and shot a 14-minute sex scene.
According to the report, Lindsay once partied with Lady Gaga until 5:30 AM ... when she had a 6:00 AM call time. She eventually showed up to the set at 9 AM, but left soon after a doctor said she was too sick to film.
Gaga posted a picture of her night with Lindsay on her website last July, along with the caption, "I love to stay up late and take pictures of beautiful celebrities."
We reached out to Lindsay for comment -- but so far, no response.