During a decompression drill, with the entire ship’s crew tethered to their air lines, Glyndower puts everything on hold for a twenty-minute lecture on the Novaya Europan menace, which quickly degenerates into anecdote (fairly relevant anecdote, to be fair). Morrish has a quiet word with the medical officer, Surgeon-Commander Sharpley, who comments carefully on the distinction between “suggestive”, “indicative” and “actionable” behaviour.

Morrish spends much of his off-duty time with the simulators, looking over Glyndower’s engagements. He wasn’t a stellar performer at BRNC, but he repeatedly found himself in situations where there was an obvious right thing to do, he chose to do something else, and he was proved right, with more tactical success and lower casualties than simulations of what the book said was the correct solution.

Some trials are being made using ships’ boats (with the passenger seating removed and replaced with comms gear) to control drone fleets. A civilian ship intrudes slightly on the exercise area, and Glyndower orders a close pass; Morrish and Tovey wrestle the drive into submission. Glyndower calls for a boarding party, and Stonely goes along with Winthrop-Chase’s Marines; the captain (a Novaya Europan) is startled and annoyed by what is certainly an unusually strict response, and talks about complaining to his embassy, but doesn’t do anything silly; indeed, he blames everything on an apprentice navigator, whom he’s happy to hand over. There’s nothing obviously amiss, but Glyndower calls for “rivet by rivet”; there are some laser emitters camouflaged as “structural members” in the hold, and the outside team finds an isolated passive receiver that’s been collecting drone control data; the captain claims to know nothing about either, but the ship is impounded anyway.

There are further incidents, including a low orbital pass where Glyndower calls for a sudden bridge casualty and the Action Information Centre has to take over flight control; the ship does end up taking some friction damage to the forward armour, though Tovey spreads it out enough to avoid any burn-through. There wasn’t any prior announcement of the bridge casualty, but with Glyndower there never is; that’s the point.

Things come to a head when a Novaya Europan light cruiser is transiting the system, heading out from Sol; Glyndower calls for an intercept and attack run, and Captain Thompkins blinks and complies. As the ships draw closer, Glyndower calls for antimatter missiles to be loaded; Thompkins looks briefly lost, and Surgeon-Commander Sharpley drifts unobtrusively onto the flag bridge. Before the order to fire can be given, Sharpley starts the formal wording to remove Glyndower from command; Glyndower ignores him, and calls on the Marines guarding the flag bridge to “remove this mutineer”. They look to Winthrop-Chase for clarification, which he (reluctantly) gives: they are to assist the doctor. Before he’s restrained, Glyndower manages to seal the flag bridge, and send a message to the rest of the flotilla advising them that Canopus’ officers have mutinied; Captain Thompkins explains the situation, and while there will clearly be formal enquiries there is at least no shooting today. The assistant medical officer arranges for intruder control gas to be deployed on the flag bridge, and when the doors are eventually got open everyone inside is unconscious. In spite of the records made by their uniforms, everyone involved is required to make statements for the Admiralty Board.

Some time later, Morrish is at a party at Government House when he sees Alex Ramprakash confronting an older man; she seems to be accusing him of being a spy, and he’s protesting that he doesn’t know what she’s talking about. The exchange ends with neither particularly happy, and Morrish scoops up Alex; it seems that the other fellow is a Geoff Hutchins, an administrator in Government House, and she’s seen him accessing data he shouldn’t be.

Morrish looks around, and sees Commander Doyle, “Uncle” or the senior intelligence type, nearby, and explains what he’s just observed. Doyle confirms that big ears can be brought into play, but he’s known to Hutchins, and doesn’t have boots he can put on the ground for plain old following and noting of contacts. Morrish offers to help out there, and has some colleagues he can get involved.

Hutchins leaves the party, and the four (Morrish gathering up Alex too with the promise of taking her up on that flyer trip they’d talked about) follow him down the beanstalk and round the downport. If he’s spotted them, he doesn’t react, though he does spend several hours drinking cheap synthetic coffee; they shop and wander. Eventually he heads into an implant computer shop, with a small front area and presumably operating chairs behind; he stays out of sight for an hour or so before coming out again and going back up the beanstalk. Morrish and Alex take the flyer trip (and he’s still not quite sure what to make of her); the others trail Hutchins, and give the nod to Doyle once Hutchins is back inside Government House.

All seems well until all four of them are called aboard to Captain Thompkins next day; Doyle is with her. She raises an eyebrow; he confirms that he’s never seen them before. (He looks just like the Doyle that Morrish met earlier, except for the recent laser scar on one hand.) It seems that last night his double attempted to assassinate him; fortunately, he was a bit faster and sneakier. At the time of the party, he was still on board the ship…

The four are thoroughly scrubbed for electronic nastiness, but this doesn’t help Hutchins, who’s completely vanished; and the computer shop seems to have been burgled and then accidentally caught fire.

The attacker seems to have been a clone of the real Doyle, with someone else’s brain and spinal cord surgically implanted; this is just about achievable with current medical tech, though it would need a ferocious drug and nanomachine regimen to prevent rejection, and even then it wouldn’t last more than a few months. Now that this is a known problem, various tests are proposed to spot future doubles: blood tests certainly, but even external scans of the brain should show up structural variations, especially if the infiltrators aren’t the same age as their doubles.