Bridge Four is a bridge crew - later an elite military unit - that becomes the heart of Kaladin Stormblessed's story in The Stormlight Archive. Originally a group of expendable slaves forced to carry bridges into battle on the Shattered Plains, Bridge Four was transformed by Kaladin's leadership into a band of fiercely loyal soldiers. Their defiance of the brutal bridgeman system and their refusal to break under impossible conditions makes them one of the most celebrated groups in the series. After earning their freedom, Bridge Four's members become the personal guard of Dalinar Kholin and, later, some of the first new Knights Radiant in millennia. The crew's members - including Teft, Rock, Sigzil, Lopen, and Skar - each bring their own backgrounds and struggles.

The Knights Radiant are an ancient order of warriors who bond with spren - sentient fragments of the cognitive realm - to gain access to Surgebinding, the magic system of Roshar. Each order is defined by its patron Herald, its associated spren type, and the two Surges it can manipulate. There were ten orders in total, including the Windrunners, Lightweavers, Bondsmiths, and Edgedancers, each with their own ideals, culture, and role in defending Roshar against the Desolations - periodic invasions by the forces of the Shard Odium. The Radiants abandoned their oaths millennia before the events of The Stormlight Archive in an event called the Recreance, but across the series, new Radiants begin to emerge as the ancient threat returns. Kaladin, Shallan, Dalinar, and Jasnah are among the first of this new generation.