From the publishers webpage:
The war for Medrealm is entering its final stages. As the balance tips ever further towards the Galian Federation, offworld mercenaries and their Medrealmer allies are trapped in the Rammline Pocket. Rumours abound that the Galians are not honouring repatriation bonds.
The nearest repatriation haven is hundreds of kilometres away, and evacuation by grav vehicle is not possible unless Galian aerospace interdiction can be evaded. The choice is between surrender and a desperate lunge up the Aix Valley to buy time for a desperate enterprise – a Verloren Hoop, or Forlorn Hope.
The Travellers are sent to infiltrate the high slopes of the Transaix Pass, collapsing the mountainside ahead of the advancing Galians. From there they are flung into battle, plugging a hole in the defensive line. With the situation stabilised they can begin the most dangerous phase of the operation. Success might open a window for evacuation, but the odds are stacked against the Travellers.
Requires the Mercenary box set.