It seems one of the reasons the OP likes Dan Brown is his simple English, even if sometimes incorrect. Many of our favorite gripping authors use more sophisticated English and may not be as un-put-down-able as DB to a foreign reader.
I liked the E.R. Burroughs suggestion. When I think of simple prose and gripping together I think of those books that I enjoyed when I was younger, like his Pellucidar or Tarzan series. Or Johann Wyss's Swiss Family Robinson. Or Doc Savage (various authors). Yes, these are all older and the pacing doesn't match modern sensibilities.
You already said no to Patterson and Koontz, two current authors with some gripping novels. Maybe try Harlen Coben, Brad Thor, David Baldacci, or Lee Child.
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