As author Brad Meltzer finished more than a half-dozen stand-alone thrillers, he apparently decided to do what thriller-authors such as James Patterson and Daniel Silva do.

Create a series.

Why not plug readers into the next novel by hooking them on the characters in the current novel?

Patterson has made a fortune and opened the door to other series and stand-alone titles with his Alex Cross books. Silva has been chronicling his super spy/art restorer Gabriel Allon for more than a dozen books.

So why not Meltzer?

A couple of years ago, he introduced Beecher White, a young, government archivist working in Washington, D.C. Beecher is introduced to the Culper Ring, a secret society founded by George Washington to protect the presidency. The Culper Ring still exists more than 200 years later and it needs recruits.

In “The Inner Circle,” Meltzer laid the groundwork for integrating Beecher into the Culper Ring but he also created a mystery involving the military death of Beecher’s father many years earlier, a relationship with a childhood friend whose father killed a First Lady during a presidential assassination attempt, and the rise of a malevolent president.

These elements continued through the second installment, “The Fifth Assassin.”

And do so again in the latest novel, the recently released “The President’s Shadow.”

Here, Meltzer concludes the majority of the mysteries spread across the three books, but not everything. Meltzer leaves a few loose ends.

Which begs the questions.

Is Meltzer finished with Beecher White and the Culper Ring? Was it a trilogy?

Or does Meltzer have new adventures for Beecher and the Culper Ring? Is it a longer series?

Hard to tell. It could go either way. Rumor said it was initially intended as a trilogy, but …

Meltzer will definitely be back with more books in the future, but readers may have to wait and see if Beecher White will be back, too.