Star Trek: TOS: Rihannsu Books in Order

The Rihannsu books are Diane Duane's Romulan saga, and for many readers they are the heart of her Star Trek work. The title uses her own term for the Romulans, which tells you something immediately: these books are not content to use the species as flat antagonists. They build a culture, a language, a history, and a worldview.

That is the big draw.

The series begins with My Enemy, My Ally, where a Romulan commander and Kirk's Enterprise are pushed into dangerous cooperation. From there, the books keep widening. Questions of honor, secrecy, power, memory, and political survival move to the foreground. By the time you get deeper into the sequence, the story is spending as much time inside Romulan life as it does beside Starfleet.

Ael is one of the major anchors early on, and she helps set the tone. These are books interested in adversaries who are also fully realized people. The tension often comes from divided duty rather than simple evil.

The later books lean even harder into internal Romulan politics and the long consequences of earlier events. That makes the whole line feel more like a connected epic than a loose stack of tie-ins.

If you like Star Trek novels that do serious cultural worldbuilding, this is the page to open first. If you want straight shipboard adventure, these still have that. But their lasting power comes from how completely they imagine the Rihannsu.

That is why the series still gets singled out.