Understanding it: Great summary of hidden/missing elements of the plot

Found this on a Wikipedia "Talk" page, and it's very informative. Don't know who wrote it.

The film leaves many questions of action and motivation open without explicit answers. The following is a conjectured timeline of events and motivations (all spoilers):

Terry Lennox is a small-time local kid, a childhood friend of Philip Marlowe; he has managed nevertheless to marry a rich woman, Sylvia, with powerful family/friend connections. Because Terry is vain, handsome and stylish, and because the film begins and ends with "Hooray for Hollywood" on the soundtrack ("Where any office boy/Or young mechanic/can be a panic/With just a good-looking pan"), there may be a suggestion that Terry had brief success as an actor, which would have given him entree to high society and a taste for the finer things.

While living in style at the Malibu Colony with Sylvia, Terry is running money across the Mexican border for gangster Marty Augustine, possibly to settle gambling debts, perhaps just for thrills or pocket money. At the same time he is carrying on a passionate affair with his neighbor Eileen Wade. Eileen loves Terry: to Terry the affair may simply be a matter of trading up, since the Wade fortune is greater than Sylvia's and Augustine's combined.

Eileen's husband Roger discovers the affair, hits her in the face, then storms off to tell Sylvia. Sylvia reacts hysterically, threatens to leave Terry and inform the police of his gangster activities. At this point Terry knows he is finished in L.A. His wife's connections are powerful enough to make life impossible for him; more than that, he knows Augustine will never let him live to be taken in by the police and rat the gang's operation out. He could just take Marty's $355K and run, but he is accustomed to luxury and the support of a beautiful woman. The only way to salvage his situation and remain on top is to cement his relationship with Eileen, and that means Sylvia must be eliminated. He viciously kills his wife and gets Marlowe to drive him to Tijuana to avoid the risk of the police ID'ing his car and picking him up once Sylvia's body is found.

Once in Tijuana Terry calls Eileen and tells her what he's done, and makes her believe it was all for her sake. Eileen promises to help get him out of his jam.

Eileen, as the brains of the pair, comes up with a plan, and the only two people who might interfere with it are Marlowe and her husband Roger. After talking with Sylvia, Roger got drunk and passed out; Eileen calls Dr. Veringer and asks him to pick Roger up and put him on ice for a few days. She then informs on Marlowe to the police about his role in helping Terry escape, and either persuades or bribes them to accept that Roger was in rehab before Sylvia was killed, and to pick Marlowe up and hold him for three days. Soon afterward, Marty realizes his money is missing, and as he knows or suspects Eileen was involved with Terry, he presses her for information.

Nevertheless, during those three days she manages to slip out of town to meet Terry in Tijuana and execute her plan. They go to a small town with bribable officials and fake his suicide. She then sets him up in a luxury hacienda and tells him to wait for her while she settles things back in the US. She takes the $355K because although Roger is wealthy he is cash-poor at the moment, and she will need her own money for expenses. She gets Terry to write Marlowe a note and seals it up with a $5000 bill from the stash.

Now Eileen needs three things. She needs to avoid letting the police realize she was involved with Terry, she needs Marty to lay off her, and she needs Roger to be dead so she can possess his fortune and use it to support her new life with Terry. Marlowe is her key to all three of these needs.

Once Eileen is back in L.A., she drops the note and the $5K bill in Marlowe's mailbox. She rats out Marlowe, who now has the $5K note conveniently planted on him, to Marty, thus distracting him from her.

Veringer demands payment for his special service; Eileen refuses, knowing that Veringer will thus keep Roger bottled up until Roger himself pays. This is the start of her program to subject Roger to a systematic series of humiliations with the intent of goading him into suicide, which she knows he is near to already.

She calls Marlowe to find her husband, pretending she doesn't know where he is. She gradually draws Marlowe into her life, charming him, letting Roger get to like him; then after giving Roger false hope of reconciliation, she pays unseemly attention to Marlowe and makes Roger suspect she's slept with him.

The confrontation with Veringer at the beach party is the last stroke. Roger gets drunk, then wakes up late in the evening to find his wife having a candlelit dinner with Marlowe. In despair Roger plunges into the surf, drowning himself. Marlowe, drunk and horny, buys Eileen's act and believes that Roger was having an affair with Sylvia and killed her.

Now Eileen only has to give Marty back his money, and she has achieved her goals. Roger was the only person who knew she was involved with Terry, now he is dead, and she has his fortune to boot. She has charmed Marlowe out of his suspicions, manipulated him as she has always been able to do with men. Now that she is rich she has no more need of Marty's money and drops it off to him.

But her inner coldness, which her husband observed and which allowed her to do all these things, is her undoing. She is too quick to drop off the money, and puts her house up for sale immediately. Marlowe thereby remembers what he should have, that everything in L.A. is an illusion and an act, and he realizes he's been had.

That's ok with him. What isn't ok, however, is the fact that he was used as a proxy for the killing of Roger Wade by his best friend. That's what drives him into a murderous fury and prompts him to kill Terry.

The Long Goodbye is what comes before the Big Sleep: life, which is simply a precursor and prelude to death. All of the characters' strivings to reach for more and better life result only in the hastening of its end. Only Marlowe, unstuck in time and a disconnected observer of life, is able to perceive the shadowplay.