Which C.S. Lewis novel features the character Mark Studdock at a modern university?

The C.S. Lewis novel featuring Mark Studdock at a modern university is That Hideous Strength.

Published in 1945, That Hideous Strength is the third and final volume of Lewis's Space Trilogy. Its story shifts from the planetary settings of the first two books to a modern English university environment. Mark Studdock is a sociology professor who becomes involved with the National Institute of Coordinated Experiments, a powerful and sinister organization.

The novel combines science fiction, social criticism, Arthurian elements, and Christian themes. Mark's career ambitions and desire for acceptance make him vulnerable to institutional pressure. His wife, Jane Studdock, follows a separate storyline involving dreams, marriage, and a search for meaning.

The title echoes a line from a sixteenth-century poem by David Lyndsay. Although the novel belongs to a trilogy, it is more socially and politically focused than Out of the Silent Planet or Perelandra. Its university setting is therefore a major part of its identity.