All four books are set in the Star Trek universe and share similar themes of exploration, diplomacy, and conflict resolution. "A Time to Sow" and "The Badlands" explore the challenges of navigating the unknown and discovering new worlds, while "The Photostory" focuses on the power of communication and storytelling in bringing people together. "Stargazer" delves into the personal struggles and relationships of a captain and his crew. All four books highlight the importance of teamwork and ethics in achieving common goals.