In the series opening, we get to know Caleb Temple losing his sister in an unexpected way, and then his father dying in prison being the prime suspect of his daughter's death. Lucas Buck, the all-around town sheriff steps up for Caleb's adoption, while Caleb runs away from his wannabe adopter. A long lost cousin returns to Trinity to help her kin, and the new town doctor starts to discover that the whole town is in a web with the sheriff in the center.
The local coroner records an autopsy report as ordered. Caleb keeps fleeing from Lucas Buck, and finds out that his father is dead by seeing his grave next to his sister's. His sister's apparitions guide him to an abandoned house with someone tied down. Merlyn guides Caleb into helping that person.
Carter got away with molesting a girl, via Sheriff Buck's influence, but 17 years later, stalls about providing his own 15 year-old daughter as the Sheriff's go-fer. When junkyard owner Carter doesn't meet Buck's midnight deadline, immediately Carter's wife is maimed in a household accident. Buck offers to buy the orphaned Caleb an elaborate science project, while Caleb's dead sister & Dr. Crower counsel him to focus on learning, not cheating to win.
Gail accuses Sheriff Buck of foul play when she learns that her childhood friend Holly Gallagher, who was Sheriff Buck's girlfriend, was with her just before she mysteriously drove her car off a bridge. As Lucas takes Gail for a ride to demonstrate for her where and how this happened, he takes her by surprise with a kiss. Caleb goes up against his friend Boone in an archery competition, and Deputy Ben must deal with the abusive behavior of his ex-wife's current husband.
Caleb is intrigued by a strange "potato boy," a deformed child who lives alone in a creepy house in Trinity but whose sweet singing voice can be heard in the distance. Meanwhile, we get a little insight into Deputy Ben's frustration with his job and having to lie for Sheriff Buck's misdeeds, Selena Coombs' own personal fall from grace, and the guilt that Dr. Crower carries with him for the death of his wife and child.
The bones of one of Trinity's residents are found at the remains of the burned-out Temple home, which now belongs to Lucas. The victim's brother-in-law, Lt. Drey of the State Police (guest star Bruce Campbell), comes to Trinity to investigate, and Selena Coombs is a suspect. Lucas, meanwhile, tempts Caleb with a casket of cash.
Some houligans are staying at the boarding house where Caleb and Dr. Crower live, and they're shaking down the town's business owners for cash. Sheriff Buck takes note and begins to deal with him in his own special way, especially after they threaten Caleb, who discovers their stash of cash in one of the rooms at the boarding house. When the bad guys corner Caleb in his own room, they get a scare from the little boy, however!
Matt Crower is haunted by the memories of his wife Lily and his daughter Claire, who died because of his drunk-driving crash. The sheriff makes him an enticing offer - the chance to go back and see them and say goodbye. Matt takes the offer, but he wants oblivion, which the sheriff won't grant. Caleb, meanwhile, is intrigued by his elderly neighbor whom he thinks has buried a body in his pumpkin patch.
Deputy Ben's brother Artie breaks out of the psych ward and terrorizes the people in Trinity, taking Sheriff Buck, Dr. Crower, Gail and Caleb hostage at the hospital. He was shot while robbing an electronics store, and he demands Dr. Crower remove the bullet. He also has explosives buried in his stomach, set to go off at 11 o'clock that evening.
Merlyn Temple badly wants to be alive again and to feel what human beings feel. She steals the soul of the unborn baby of Gail's friend Christie, who is in town visiting Gail and close to giving birth. With this soul, Merlyn spends time with an intriguing boy blowing through Trinity on a motorcycle, Ray. But Caleb realizes it's the soul of Christie's baby that Merlyn has stolen and must try to convince Merly to give it back before the baby dies.
With thoughts of why she originally came to Trinity still on her mind, Gail is researching the 1976 fire that killed her parents, convinced that Lucas caused it. But she gets help from an unlikely place - Lucas himself. As she digs deeper at her family's summer home and at the newspaper offices, she finds in her visions that the truth is uglier than she realized, and it has nothing to do with Lucas.
A local talk radio host wants the sheriff's help in getting a TV show for him and his on-air partner, his wife. When Lucas says no, the host, Mel Kirby, finds a way to blackmail him through Ben. But Mel will pay the price for that. Caleb, meanwhile, gets an idea from Ms. Holt on how to reach Merlyn, who seems to be trapped somewhere in hell.
Merlyn's back, and she's hell-bent to get Lucas. The sheriff is on his own bent, though, to get a lawyer who screwed him over. He corners that lawyer, Bryan Hudson, into selling his family's property and evicting a longtime friend, Bertie.
A plague hits Trinity, and Dr. Crower becomes infected and starts going wild, ranting about repentance. Gail succumbs to her passions with Sheriff Buck, and he's only too happy to oblige. A new doctor shows up in town from the CDC to deal with the plague, Dr. Billy Peale.
Dr. Crower decides to investigate Merlyn's murder and becomes even more curious after a woman checks herself into the hospital claiming to be Sheriff Buck's mother (guest star Veronica Cartwright). She wants Dr. Crower to kill Sheriff Buck, but the tables are turned on Dr. Crower. Sheriff Buck uses Matt's plague sickness of a week or two ago to his advantage.
Sheriff Buck takes Caleb on a fishing trip in a neighboring town, but they encounter the kidnappers of a corporate mogul. One, Ted (guest star Ted Raimi), has shot the kidnappee, but he's quickly subdued by the sheriff before his two partners menace the cabin from outside. Selena comes to the cabin, having been led to believe by Lucas that her new boyfriend Dr. Peale is there, and Gail and Dr. Peale soon follow, afraid that something is continuing on with the sheriff and Selena.
Every time he turns around, Deputy Ben sees Merlyn. She has something to show him: her mother's work with needy children at an old abandoned house in Goattown. She wants Ben to pick up that work, at least where one particular young girl is concerned. That girl has also been bullying Caleb and Boone at school. Gail continues her dalliance with Lucas, while Selena dates Billy.
Gail tells Lucas she's leaving town, with Caleb, but then discovers she's pregnant with Lucas' child! But is the sheriff still wrapped up in Selena? Is Selena still in love with the sheriff? That seems to be the suspicion, as Dr. Peale asks Selena to go away with him to Uganda to work among the needy. She pulls a no-show at the airport. As Gail deals with her pregnancy, she is scared of what kind of monster her baby might be. Then Lucas has revenge on his mind for Selena, whom he sees as cheating. He puts her under a life-threatening spell.
After another run-in with Merlyn, Sheriff Buck conjures up the spirit of the Boston Strangler, Albert DeSalvo, to deal with her once and for all. But DeSalvo has an appetite for some other females in town, including Gail. Lucas goes off to a convention out of town, meanwhile, and Ben fills in as sheriff.
Sheriff Buck is giving Caleb lessons on "the Buck" and how there's only one for every generation. This causes Caleb to really begin to embrace what seems to be his evil destiny. The pharmacist at the hospital, Yancy Lydon, is angry that Sheriff Buck has withheld the files on his sick wife from him. She's been comatose for two years. Yancy attacks the sheriff at his house, stabbing him in in "third eye," but before he dies, Lucas whispers something to Caleb. With the sheriff then dead, Caleb turns into a monster in his place. Later, in Lucas' grave, though, the sheriff...
Caleb moves into Sheriff Buck's house to take over his evil mantle and, when learning from Selena that Gail is pregnant with Lucas' child, has her lured to the house. Dr. Peale has analyzed Lucas' blood work, and after a tip-off from Merlyn, Deputy Ben helps Billy dig up Lucas, who then goes after Caleb to change him back to the way he was.