Gregory Roarke and his Kadolian partner Selene are back. They are still crockets, exploring uninhabited worlds for new resources, but they are no longer freelancing.

“The Icarus Twin,” a science fiction novel by Timothy Zahn, picks up from where the previous book in the series “The Icarus Plot,” left off. They are now on salary with the Icarus Project. They are still seeking valuable undiscovered planetary resources, but that is now a cover story. Their real mission is to discover Icarus portals.

These portals, left behind by a long-dead alien race, allow instantaneous teleportation between different points in the universe. Selene’s sensitive sense of smell can detect the presence of portal metal. Their standard atmospheric sampling is an under-the-radar way to hunt portals. It must be done secretly because the Patth, a spacefaring race with a near-monopoly on interplanetary shipping, also want portals. Controlling portals are the only way they can maintain their shipping stranglehold.

Someone appears to be hunting Roarke and Selene, though. They have accumulated enemies interested in them. That becomes clear when someone snatches their biosphere sampling probe as they are dragging it through the atmosphere of a new planet. They are being followed.

The trackers might be the Patth. Or the crime boss the pair previously worked for. It might be some of his associates or rivals. It might be a new entrant into the field. A bounty hunter named Easton Dent has been frantically trying to arrange a meet-up with Roarke, but is not revealing why.

The Icarus Group convinces Roark to meet Dent. The rendezvous goes badly wrong, with Iykams, Patth enforcers arriving before Roarke can discover why Dent want to see him. Dent disappears shortly after the two meet as Roarke, Selene, and Dent seek to evade the Iykanms.  Then Roarke gets framed for Dent’s murder. Except the dead man is not Dent – just someone who closely resembles him.

After escaping from prison Roarke want no more to do with Dent. There is one problem. Selene smelled traces of Portal metal on Dent. Additionally, both the Patth and a crime syndicate is after Roark. It becomes a game of hide-and-seek as Roarke tries to find Dent while evading the groups hunting him.

“The Icarus Twin” offers a fast-paced adventure that is every bit as exciting and entertaining as “The Icarus Plot.” If you are looking for a mix of action and mystery, read it.

“The Icarus Twin,” by Timothy Zahn, Baen, 2023, 320 pages, $28.00 (Hardcover), $9.99 (E-book)

This review was written by Mark Lardas, who writes at Ricochet as Seawriter. Mark Lardas, an engineer, freelance writer, historian, and model-maker, lives in League City, TX. His website is marklardas.com.