BIG Spoilers***Setting aside the improbability of angels and demons there are some plot points that bothered me as I watched last night, not he least of which were the many crimes Grace committed. Here is a run down: breaking and entering the home of the child she recently killed, stealing a photo and bracelet, peeping on the grief of the bereived mother, illegally entering the home of her neighbor and tying her to a chair then leaving her--possibly to die--stealing her drugs, using said drugs, leaving her dog Gus locked in the house without making arrangements for a dogsitter, finding a dead body and not reporting it to the authorities, transporting said body across international boundries and state lines illegally, not to mention the bloody attempted murder of Hut Flanders and intentional detonation of a huge bomb in a busy commercial area.
Then there is the whole time line problem. Grace was only missing between 36 and 72 hours. In that time she tied up Neely, smoked crack, arranged to have her Porche crushed, broke into and hid in the mother's house until she could escape without being detected, procured a red pickup truck, drove or flew to a Mexican border town near a beach. That means it is either Tiajuana, 1350 miles, 20 hour drive, or Brownsville and South Padre Island (700 miles, 12 hour drive) went to a quencinera, found Neely's body, tried to commit suicide by drowning. Moved the body from the ally to a vehicle or plane, delivered it to New Orleans (1800 miles from Tiajuana, 700 miles from Brownsville), arranged for burial, morned over her grave and returned to Oklahoma on the same day that her house burned down.
Even if you allow that Earl may have helped with more than driving, it stretches the imagination. Plus Earl has never helped with realistic kinds of travel before. It was always more like the scene where he invited her to eat on the beach. His trips with Grace took place in a kind of spiritual world where even a nuclear blast would go unnoticed by the rest of the world. At the end of each trip she was still in her home as if she never left. Therefore we must conclude that Grace never really went to Mexico, tried to commit suicide (washing machine story notwithstanding), went to New Orleans, or met Potter and discussed how he found her body. All of that was part of her fantasy or out-of-body-experience and if that was, then the motive probably was as well. The motive was finding the girls photo, so she never broke into the mother's house or spied on her crying. All of this occured after she stole Neely's drugs and used them, so I submit it was all a hallucination. From that moment on we're are in Wonderland.
First, Grace is cleaning house, something she's never done before, Rhetta finds Neely has been the victim of a serious crime and even though she is a sworn officer, she makes no attempt to report it, neither does it occur to her that Neely might try to take revenge or need counseling. Rhetta finds drug parafinallia in Grace's home, but no drugs. What happened to the drugs? If Grace used it all, she was high a long time or she OD'd. Then Rhetta tells people Grace will be alright and not to go check on her? That is not like Rhetta.
I think what really happened was she never left town, Neely didn't die, Grace accidently set the house on fire while doing drugs. She rescued her dog--and maybe her nephew--from the fire before she went into a coma and died in the hospital dreaming she was fighting pure evil.
If not, then the writers were on crack.