Ready Player One meets The Fault in Our Stars in this gripping blend of science fiction and fantasy about a couple's desperate attempt to hold onto one another against the greatest enemy of all. An experimental new technology called the SynAPP, developed by the company Synerdyne for palliative care, allows users to enter a simulation generated directly in their minds. There patients escape to a virtual environment, dubbed Elysium, where they participate in a communal structured dream, experiencing a life free from injury, illness, and physical limitations.

Sam and Marcus, founding members of Synerdyne, have found another use for the SynAPP. Instead of the mundane and curated Elysium, they visit a gritty fantasy setting, affectionately called Sam's World, originally developed as part of Synerdyne's now-defunct entertainment division. It is a savage land, filled with danger and adventure, where Sam takes on the mantle of Morrigan the Barbarian. When visiting she escapes the cancer that has left her suffering and bedridden, interacting with Marcus as though nothing has changed in their relationship.

The unexpected involvement of an entrepreneurial billionaire named Clive Ellison, who expresses interest in Synerdyne and its SynAPP technology, complicates matters. However, as Sam's prognosis grows more dire, Marcus discovers that Sam's World could hold the key to her survival, and Clive Ellison might just be the answer to all their problems. But they must act quickly before Sam's time runs out.