In February of 2161, as a part of their open marriage, Doug is on a hunting trip with his paramour, Melissa Madden, as Lili awaits the arrival of Malcolm Reed for their own vacation. Lili's children, Joss Beckett and Marie Patrice Beckett are waiting for their babysitter, a Calafan named Yimar, to take them to the zoo on Lafa IX.
As the couples are reconnecting, the action shifts to March 27, 3109, where time traveler Richard Daniels is visiting his sister, Eleanor Daniels, who is a docent at the Temporal Museum on Lafa II. While she is lecturing a group of schoolchildren about Hoshi Sato (mirror)'s six children, Eleanor holds an elaborate sword named Ironblaze. As she speaks, Ironblaze begins to disintegrate, a sure sign that there has been a change made in time.
Richard contacts the Temporal Integrity Commission and speaks with his superior, Admiral Carmen Calavicci. Carmen confirms that there are major problems and he needs to return to headquarters. He does so, and is given a new ship, the USS HG Wells, which runs on chronitons, an invention of the Chief Engineer, the part-Gorn Kevin O'Connor.
While flying to 2161, Richard reads up on the mission, learning that Empress Hoshi has had two of her crew members in 2161, Chandler Masterson (mirror) and Lucy Stone, fire a pulse shot, which is composed of phased dark matter. The intention is to punch a hole to the prime universe, in order to obtain more ships like the USS Defiant (NCC-1764). From their perspective, it does not seem to work. However, Richard knows better, that it has succeeded, not in opening a portal, but in creating incoherent time.
The ship returns to the Lafa System in 2166 and another pulse shot is fired. This time, a portal is opened during a winter sledding party and three persons cross over – Joss, Marie Patrice and their half-brother, Thomas Digiorno-Madden. Joining them is a fourth child, Declan Reed. As the children enter, José Torres (mirror) enters from the Mirror universe, and massacres the civilians at the sledding party.
A third pulse shot is fired in 2178, intended to alter time. Richard is expressly forbidden from going to the Mirror universe because he has a temporally paradoxical child, Jun Sato. In order to allow Jun to live, the Terran government required that Richard not return to the mirror during Jun or Hoshi's lifetimes (In Between Days: First Born).
Therefore, Richard enlists Doug and Lili to go to the mirror to retrieve the children and help to close to inter-universal gap. They are to be sent to 2178 first, as temporal incoherence has made it difficult to pinpoint the exact moments of the temporal divergences in 2161 and 2166. But the one in 2178 is independently verified, as it includes the destruction of a major Calafan artifact, the Cuff of Lo.