Reading order
| # | Title | Published | Author | Buy on Amazon |
|---|---|---|---|---|
| 1 | Unwrapping the Castelli Secret | 2015 | Carol Marinelli | Buy |
| 2 | Brunetti’s Secret Son (Secret Heirs of Billionaires) / Christmas at the Chatsfield | 2015 | Carol Marinelli | N/A |
| 3 | Brunetti’s Secret Son/ Christmas at the Chatsfield | 2015 | Carol Marinelli | Buy |
| 4 | The Secret to Marrying Marchesi | 2016 | Carol Marinelli | Buy |
| 5 | Demetriou Demands His Child | 2016 | Carol Marinelli | Buy |
| 6 | The Desert King’s Secret Heir | 2016 | Carol Marinelli | Buy |
| 7 | The Sheikh’s Secret Son | 2017 | Carol Marinelli | Buy |
| 8 | The Innocent’s Shameful Secret | 2017 | Carol Marinelli | Buy |
| 9 | The Greek’s Pleasurable Revenge | 2017 | Carol Marinelli | Buy |
| 10 | The Secret Kept from the Greek | 2017 | Carol Marinelli | Buy |
| 11 | Carrying the Spaniard’s Child | 2017 | Carol Marinelli | Buy |
| 12 | Kidnapped for the Tycoon’s Baby | 2017 | Carol Marinelli | Buy |
| 13 | The Greek’s Secret Son | 2018 | Carol Marinelli | Buy |
| 14 | Claiming His Hidden Heir | 2018 | Carol Marinelli | Buy |
| 15 | The Secret the Italian Claims | 2018 | Carol Marinelli | Buy |
| 16 | Demanding His Hidden Heir | 2018 | Carol Marinelli | Buy |
| 17 | The Heir the Prince Secures | 2018 | Carol Marinelli | Buy |
| 18 | The Italian’s Unexpected Love-Child | 2018 | Carol Marinelli | Buy |
| 19 | Wed for His Secret Heir | 2018 | Carol Marinelli | Buy |
| 20 | The Baby the Billionaire Demands | 2018 | Carol Marinelli | Buy |
| 21 | Married for His One-Night Heir | 2018 | Carol Marinelli | Buy |
| 22 | The Secret Kept from the Italian | 2018 | Carol Marinelli | Buy |
| 23 | Demanding His Secret Son | 2019 | Carol Marinelli | Buy |
| 24 | Sicilian’s Secret Son | 2019 | Carol Marinelli | N/A |
| 25 | The Sheikh’s Secret Baby | 2019 | Carol Marinelli | Buy |
| 26 | Claimed for the Sheikh’s Shock Son | 2019 | Carol Marinelli | Buy |
| 27 | The Sicilian’s Secret Son | 2019 | Carol Marinelli | Buy |
| 28 | Shock Heir for the King | 2019 | Carol Marinelli | Buy |
| 29 | The Maid’s Spanish Secret | 2019 | Carol Marinelli | Buy |
| 30 | Sheikh’s Royal Baby Revelation | 2019 | Carol Marinelli | Buy |
| 31 | Cinderella’s Scandalous Secret | 2019 | Carol Marinelli | Buy |
| 32 | Unwrapping the Innocent’s Secret | 2019 | Carol Marinelli | Buy |
| 33 | Proof of Their One-Night Passion | 2019 | Carol Marinelli | Buy |
| 34 | The Italian’s Unexpected Baby | 2019 | Carol Marinelli | Buy |
Secret Heirs of Billionaires is one of Harlequin’s themed continuity series, running 34 books over four years. The premise is the same each time: a billionaire finds out he has a child he never knew about, and the resulting confrontation with the mother sparks a romance. Carol Marinelli contributed several entries, and the roster includes many of Harlequin Presents’ best-known authors.
The books are independent of each other, so readers can pick up any entry without needing the others. The appeal is in seeing how different authors handle the same basic setup, whether the hero is a Greek tycoon, an Italian count, or a desert sheikh.