The Big Sleep ending explained (spoilers)

[Michaelderne 0]

Marlowe (Bogart) deduces that Carmen murdered Regan, and that Vivian was uncooperative with him because she was trying to protect her sister by covering it up. The coverup caused six people to be killed. Marlowe and Vivian reach a compromise; Eddie Mars (accidentally killed by his own gang) will be blamed for the murder. They will also tell this to Carmen and Vivian's father to protect him from the shame. And Carmen will be sent to a mental institution instead of being turned in and facing justice.