 To get to their appointment with Degra on time, Enterprise must pass a subspace corridor which is guarded by the aggressive Kavalans. Just about to make an attempt, Enterprise is stopped by Enterprise. Their captain, Lorian, tells them crossing the subspace corridor will put Enterprise 117 years back in time and that his crew all are descendants of the original crew. He wants to make some modifications to the ship, so the time shift will not happen.