Which C.S. Lewis novel features the character Ransom and begins the Space Trilogy?

Out of the Silent Planet is the C.S. Lewis novel featuring Ransom that begins the Space Trilogy.

Published in 1938, the novel introduces Elwin Ransom, an English philologist who is kidnapped and taken to Mars, known by its inhabitants as Malacandra. Ransom discovers that the planet contains intelligent species and a moral order very different from the assumptions of his captors.

The book combines planetary adventure with philosophical and theological themes. Its two sequels are Perelandra, published in 1943, and That Hideous Strength, published in 1945. Readers sometimes reverse the trilogy’s order by naming Perelandra first because it is often remembered as the most overtly theological installment, but Out of the Silent Planet is the opening volume.