[1] Father Callahan is the local Roman Catholic priest of the small Maine town of Jerusalem's Lot.

[2][3] An alcoholic, Callahan presides over the funeral of Danny Glick, a young boy who was, unbeknownst to the townsfolk, killed by the vampire Kurt Barlow.

Local writer Ben Mears, schoolteacher Matt Burke and a young boy named Mark Petrie discover what is happening.

Callahan leads a daytime assault on the old house that is Barlow's hiding place, only to find that the vampire has vacated the premises in anticipation of their attack.

The Hitler Brothers, two hoodlums who murder Jews, black people and homosexuals and carve swastikas on their victim's foreheads, are hired to find Callahan.

But before they can finish the swastika, Callahan is rescued by Calvin Tower and Aaron Deepneau, two men who figure prominently later in Roland's quest.

After his death, he wakes up in the Way Station, where he encounters Walter o'Dim who gives him Black Thirteen, one of the "Bends" in the Wizard's Rainbow.

It transports him to the Doorway Cave outside Calla Bryn Sturgis, where he leads a new life and over the next five years attempts to teach the locals his religion.

The group is uncontrollably sucked through and separated, with Roland and Eddie ending up in Maine and Jake, Callahan, and Oy landing in New York City in the year 1999.

They nearly succumb to the suicidal whisperings, but Callahan uses his restored faith to silence the orb, putting it back into its slumber and saving their lives.

In search of a safe storage place, he and Jake move Black Thirteen to a long-term storage locker underneath the World Trade Center, with the hope that either it will stay dormant or Roland will at some point come to destroy it (rather aptly, they comment on how a building falling on it might destroy it, foreshadowing that the future terrorist attack will be the end of the crystal ball).

They go to the Dixie Pig, the restaurant stronghold of the Low Men and vampires where Susannah is being held, where they prepare to ambush the unknown forces within.

[6] Seeing the overwhelming odds against them, Callahan sends Jake on ahead to rescue Susannah while he draws their attention.

At this point, Callahan realizes what he did not understand while facing Barlow in 'Salem's Lot: the power of his faith transcends such objects.

Rather than forced to drink Barlow's blood and leaving town damned, he marks the vampire with a knife before committing suicide.

Abruptly, with a surge of electricity and a tremor, the vampire Barlow enters, kills the Petrie parents, seizes Mark and challenges Callahan.

The beginning of the miniseries shows an event taking place after most of the story; Ben Mears enters a homeless shelter in a big city and sees Callahan giving out food.

After Ben Mears destroys Barlow, Callahan then leads the remaining vampires of Salem's Lot as his new unholy congregation while the town burns around them.

The framing story of Callahan now living in a big city, working in a homeless shelter and his being pushed out of an upper storey window are clearly inspired by the events in the Dark Tower: Wolves of the Calla novel, though the miniseries does not use any of the further material featuring Callahan from the other Dark Tower books, which feature his return and redemption.

In the 'Salem's Lot film, released on Max on October 3, Father Callahan is played by veteran actor John Benjamin Hickey.

But when Mark Petrie arrives looking for holy water, telling his own story of the undead and that he was forced to kill Richard Straker, Callahan agrees to help.