In Curse Of Strahd, Atlas found shelter with the few helpful citizenry of Vallaki. He spent a few days learning about Barovian customs and the town's political situation, making sure to appear non-threatening. The morning he had prepared to leave, however, he was forced into action as the town was breached by Vampire Spawn as well as Strahd himself. He defended the city alongside Laszlo Lazarescu and met Pack, providing assistance and guidance to the group. They were clearly torn after the petrification of their friend Jarmo Maulgrave, the kidnapping of their charge Ireena Kolyana, and the fleeing of their ally Rudolph van Richten.
Realizing that these people needed help, Atlas became a member of the party, as they too were dedicated to destroying Strahd. He found that Ghalwin of the Grove quickly took a liking to him, as he provided the wayward young paladin with guidance. Shakti of the Wildhunt took longer to trust him, but he eventually connected with her by helping her understand her mother's religion and in contacting Mother Night.
Atlas met the Wachter family alongside The Pack, and felt a connection to the matriarch Fiona Wachter, who had a favorable view of Strahd. He learned through the Keepers of the Feather that the Wizard of Wines had been overtaken by Blights and dark druids, and he assisted in driving them out of the Martikov's ancestral home. The forest-folk had stolen their last Gemstone of Life Growth, a gift to the family from the Ladies Three, which caused the vineyards to grow barren. Recognizing that the Ladies may be the ancients he swore his vow to, Ghalwin promised to retrieve the family's three stolen stones, so Atlas joined him on the mission.
They went to Yester Hill, where druids and berserkers were bringing to life an effigy of Strahd. He and The Pack chopped down Wintersplinter in a near-deadly battle and destroyed the presence of the druids there; Shakti had seen this place in a vision, but The Pack were left with more questions than answers. As they traveled back to the winery, he noticed that Ghalwin had begun changing. He had secretly made a pact with the Dark Power Yrrga, and Atlas tried to mediate Shakti's straining relationship with her brother.
During this travel, Atlas had a destiny-changing conversation: Strahd von Zarovich appeared from the shadows during his watch. The Vampire lord welcomed Atlas, and seemed to indicate he wished for the cleric to take his place in battle. He provided Atlas with a short Barovian Calender Timeline as well as an Invitation to dine with him, promising that no harm would come to him during their travels.
Delivering wine to Krezk, The Pack found the Tome of Strahd at the bottom of Saint Markovia's Pool, the first item needed to defeat Strahd. Atlas paged through the book, and began to form a connection to Strahd: he began to gain vampire-like abilities, his appearance became slightly vampiric, and he found himself able to access some of Strahd's memories, though this was unreliable. They also met The Abbot at the Abbey of Saint Markovia, a crazed preacher who promised three miracles in exchange for a traditional Barovian wedding dress. Through Yrrga's power, Ghalwin saw that the man was actually a corrupted Deva, so agreed to the request despite his misgivings about The Abbot's plan.
There, they also met the protege of van Richten, Ezmerelda D'Avenir, and the famed monster hunter agreed to travel with the group. They went to Khazan's tower and rescued van Richten from a Werewolf attack led by Kiril Stoyanovich; after defeating them, they learned he may have been distantly related to Shakti. After a heated discussion with van Richten, an incensed Ezmerelda left the group to explore Argynvostholt, while the rest of The Pack went back to Vallaki to clean up their loose ends.
With the help of Muriel Vinshaw, they rescued Arabelle and returned her to the Vistani Camp, making allies of the Vistani there, and defeated the Night Hags of Old Bonegrinder, setting up a new base for the Keepers of the Feather. During these adventures, Atlas had foreseen the names of two Dark Powers when combing through Strahd's memories: Delban, the Star of Ice and Hate, and Khirad, the Star of Secrets. In a moment of desperation to protect Tessa Nicoleva from Bella Sunbane's lightning bolt, he invoked Khirad, who saved her by shunting her to the Ethereal Border. Khirad occasionally provided protection to Atlas through his mysterious magic, but Atlas ultimately refused to form a pact with him, having seen what was happening to Ghalwin.
Vallaki was a town at the edge of revolution, and The Pack participated in the Riots Of The Blazing Sun, allowing Fiona to take control of the town; during the blaze, Atlas incited rioting in the crowd, and learned that Fiona was acting from a Tarokka Deck reading she was given as a child. They could not stay to defend the town or their good names, however, as Atlas learned through sending magic that both Muriel and Ezmerelda were in danger. Forced to make a choice, they knew Muriel was closer and actively in danger, so rode to Berez.
Disaster awaited them in the mire. Baba Lysaga kept Muriel in her Creeping Hut, and so Shakti and Atlas chose to sneak up to the cottage as Ghalwin and van Richten drew the witch's attention. Ghalwin immediately offended her by invoking the poems of the Ladies Three, and she attacked with ferocity, immediately casting a powerful spell to blast the paladin's mind. Atlas was exposed, hovering over the marsh, and the Creeping Hut lifted itself and smashed him down in a matter of seconds. Shakti attempted to take down the hut from within, but did not have enough time before she was chased out by the witch. She healed Atlas, offering him a slight chance at life before Lysaga flew down to him, piercing his body with magic missiles.
He fell back into the mire, bleeding out in the swamp. As he began to pass, he saw one final vision: Joana warmly extended her hand to her long-last Father, and Atlas returned home.