Reading order
| # | Title | Published | Author | Buy on Amazon |
|---|---|---|---|---|
| 1 | Attraction | 2015 | Penny Reid | N/A |
| 2 | Elements of Chemistry | 2015 | Penny Reid | Buy |
| 3 | Heat | 2015 | Penny Reid | N/A |
| 4 | Laws of Physics | 2023 | Penny Reid | Buy |
| 5 | Capture | 2015 | Penny Reid | N/A |
| 6 | Motion | 2019 | Penny Reid | N/A |
| 7 | Space | 2019 | Penny Reid | N/A |
| 8 | Time | 2019 | Penny Reid | N/A |
| 9 | Inheritance | 2025 | Penny Reid | Buy |
| 10 | Reproduction | 2025 | Penny Reid | N/A |
| 11 | Evolution | 2025 | Penny Reid | N/A |
The Hypothesis series is Penny Reid’s largest interconnected romance project, spanning eleven books from 2015 to 2025. It connects the Elements of Chemistry trilogy (Attraction, Heat, Capture) with the Law of Physics trilogy (Motion, Space, Time) and newer entries like Inheritance and Evolution. The science-themed titles reflect the academic settings and brainy characters.
Reid uses the Hypothesis framework to build a shared universe where characters from different trilogies interact. The series rewards readers who follow the full arc, with relationships and plot threads developing across multiple books.