Threshold Editions

Threshold Editions is an imprint of book publisher Simon & Schuster, a division of Kohlberg Kravis Roberts, specializing in conservative non-fiction. The imprint was co-founded by Mary Matalin, serving as its first editor-in-chief, and Louise Burke, who served as publisher until 2017.

From the Wikipedia article “Threshold Editions”, licensed under CC BY-SA 4.0.

An imprint is a brand inside a larger publishing house, often with its own editors and list. Imprints of large groups usually acquire through literary agents; read recent titles to see whether your book fits the list, then target agents who sell to it.