It is the fourth novel of Quinn's series of Regency romances about the Bridgerton siblings and tells the story of Colin, the third eldest child of the family.
Penelope spent time with Eloise Bridgerton and so occasionally encountered Colin, believing her feelings for him will always be unrequited.
Colin Bridgerton has returned from his frequent travels and Portia wonders if Felicity, the youngest Featherington sister, could marry him.
While gathering his journal, he cuts his hand on a letter opener and Penelope helps him staunch the blood.
At that evening's ball, Colin arrives intending to apologize to Penelope, when Cressida Twombley (née Cowper) announces that she herself is Lady Whistledown.
The next day, Colin heads to Penelope's home to make his apology, when he witnesses her climbing into a hired hack alone.
He has his carriage follow her to St. Bride's church in the East End, where he sees her hide an envelope in a pew.
He confronts her, reads it, and learns that Penelope herself is Lady Whistledown, writing one last column to denounce Cressida's lie.
Lady Featherington instantly misinterprets Colin's presence as an intention to propose to Felicity and misses numerous hints to the contrary.
After another amorous encounter with Penelope, Colin visits his younger sister Daphne to seek advice about love.
In the epilogue, Penelope and Colin receive his newly published travel memoir while she is working on a novel called The Wallflower.
[15] Romancing Mister Bridgerton, the fourth novel in the series, is the basis of the third season of the show, displacing An Offer from a Gentleman.
[17] Luke Newton plays Colin Bridgerton, Nicola Coughlan portrays Penelope Featherington,[18] and many of the cast from the two previous seasons renew their roles, with the exceptions of Phoebe Dynevor and Regé-Jean Page.