Mischa Barton Spotted Drinking & Partying Until 3 A.M. As Extremely Disturbing 911 Calls Surface

This is extremely concerning.
As we reported, Mischa Barton had a bit of a scare last month when she was hospitalized after exhibiting very bizarre behavior the morning after she celebrated her birthday with friends.
Following the incident, the 31-year-old claimed someone drugged her drink with GHB, which is why she says she was acting so erratically.
Now, TMZ has obtained two 911 calls from the night in question -- which seem to paint a different picture.
According to one of the celeb's neighbo