While waiting for Ambassador Corrik (expected to arrive with the requisitioned Valiant a prototype ship of the same model as the Defiant) Ramsey sets about removing the transwarp coil from the Tarsus. He is, however, interrupted by Ivers who confides that upon reflection he fears that Section 31 may have been infiltrated by changelings, much as the Romulan government was. He explains that for some time he has been troubled by Boqin’s out-of-character behavior but had no reason – until learning about Colonel Lovok – to suspect anything dire was amiss. Now, on the verge of joining Corrik in the hopes of recruiting Admiral Leyton to support a Section 31 plan against Dominion forces, Ivers fears that a changeling in the organization’s ranks will prompt the ambitious and often paranoid admiral to work against them. He asks Ramsey to take the Tarsus and its crew to Starbase 153. There, if they discover Boqin is human, they are to arrest him. If they find him to be a changeling they are to eliminate him as quickly and quietly as possible.
Thorus, meanwhile, has taken A’Tora to a holosuite to explore Alpha Quadrant culture and so that the changeling might find an appearance to mimic other than that of the recognizable, late Mr. Davis. Before long Ramsey calls them back to the ship and on their way to collect Les from Quark’s Bar Thorus spots Pehret drinking alone. After sending A’Tora to the dabo tables, Thorus approaches the Cardassian woman and asks if she has a spare data padd. She agreed, albeit reluctantly, and Thorus downloads the information they gathered from the Outrider. Then, without wasting time to reminisce, he rounds up Les and A’Tora and they rejoin Ramsey.
En route to Starbase 153, they learn from the Federation News Service that the colony New Bajor was entirely wiped out. Hearing this, A’Tora tells them that he doesn’t mind if they find a changeling in Boqin’s place and harm it. He adds that, although such an attitude is an atypical one, he doesn’t have much sympathy for the other changelings because if they catch up with him they will return him to their homeworld for judgement because he’s too unlike the rest of them.
Near Starbase 153 there is extra traffic, both Starfleet security patrols and vessels ferrying volunteers and relief supplies to the Toren following the tragic destruction of a manufacturing facility on one of their occupied worlds. After docking in the civilian section of the base, Ramsey and Thorus venture out to devise a plan of action. Upon seeing the number of volunteers carting medical supplies around, they decide to impersonate Starfleet medical officers and attempt to subdue Boqin and cart him away in a biobed. In the midst of carrying out this plan, Thorus spots Boqin walking with Vice Admiral Achille. He follows them and overhears their discussion of security assignments connected with Achille’s upcoming visit to the Federation Embassy on Regulus IV.
After disabling the starbase’s internal disruptor-fire detectors, they reach the floor with the security offices. After staging a false call for medical assistance in Boqin’s office, they barge in. Without warning, Thorus opens fire on Boqin who – perhaps not unexpectedly – turns out to be a shapeshifter and seemingly melts into a puddle that disappears under the desk. As he runs around to fire again Thorus sees the changeling beaming away. Just then the starbase’s red alert warning begins to blare along with the station-wide warning that an unknown vessel has decloaked in the station’s vicinity.
Wasting no time, Thorus and Ramsey beam back to the Tarsus and attempt to track the strange vessel. They recognize it was a Karemma transport native to the Gamma Quadrant. Thorus falsifies a code, posing as Starfleet Intelligence, and orders Starbase personnel to help destroy the enemy vessel. As both the Tarsus and the starbase fire upon the fleeing ship, an escape pod emerges from vessel. Ramsey scans the freighter as it succumbs to the attacks and finds out there are six Breen and one human aboard. He beams the human out and they are joined by the actual Boqin, who, from the state of his overall appearance, has been a prisoner for some time.