The first few months of the series centered around Victoria Winters and the search for her past, but then a couple of ghosts appeared, then a Phoenix, and finally a Vampire named Barnabas Collins. The show became incredibly popular and has since refused to die.
Copied from www.darkshadows.com
Victoria's Arrival (episodes 1-6)
Victoria Winters comes to Collinwood to serve as governess to David Collins. She is an orphan and hopes to find clues to her identity. She finds a reclusive matriarch, Elizabeth Collins Stoddard; a disturbed child, David Collins; and a town full of mysterious and frightening legends
The Revenge of Burke Devlin (episodes 1-201)
Despising the Collins' power and influence, Burke Devlin returns to Collinsport after spending time in prison. He befriends Victoria, manipulates Carolyn Stoddard, Elizabeth's daughter, and interrogates others to discover the truth about the accident that led to his conviction.
Matthew Morgan Kills Bill Malloy
and Kidnaps Victoria(episodes 46-126)
Collins fishing fleet manager Bill Malloy is killed by Collinwood caretakers Matthew Morgan after Matthew learns Malloy wants Roger Collins to confess to the car accident which sent Burke to prison. Matthew kidnaps Victoria when she discovers he was responsible for Malloy's death. Victoria is saved by the ghost of Josette Collins who joins the ghost of Malloy in scaring Matthew to death.
Laura The Phoenix (episodes 123-191)
Laura Collins, Roger's wife and David's mother, schemes to reclaim her son. Laura is a creature of the supernatural, an immortal Phoenix who almost suceeds in taking David with her as she is consumed by flames.
The Blackmailing of Elizabeth (episodes 193-275)
Jason McGuire, a friend of Liz's missing husband Paul Stoddard, returns to Collinwood. Victimized by his blackmail, Liz agrees to marry Jason, but at the last moment reveals the truth. Eighteen years before, Jason led her to believe she kill Paul and allowed Jason to bury the body in the basement of Collinwood. An Investigation uncovers no body; Paul did not die. Jason is killed after he enters the Old House to search for jewels.
The Introductions of Barnabas (episodes 202-220)
Jason's drifter friend Willie Loomis joins Jason as an unwelcome guest at Collinwood. Fascinated by the portrait of Barnabas Collins and the legend he was buried with all his jewels, Willie opens the coffin of Barnabas and accidently releases the 200-year-old vampire. Barnabas introduces himself as a descendant of the Barnabas in the portrait. With Liz's permission, Barnabas moves into the Old House and begins in restoration.
The Kidnapping of Maggie (episodes 221-261)
Barnabas meets waitress Maggie Evans and is struck by her resemblance to Josette, his love in the distant past. He abducts Maggie and attempts to recreate her as Josette so she may join him as his eternal vampire bride. With the help of a mysterious child, Maggie escapes and is confinded at Windcliff Sanitarium.
The Introduction of Julia (episodes 265-365)
Maggie's doctor, Julia Hoffman, arrives at Colliwood, posing as an historian. She discovers the secret of Barnabas and offers to cure him. When the experiments backfire, Barnabas turns on her. Barnabas attempts to kill those who he believes know his secret, but he is stopped by the ghost of his little sister Sarah.