Part one of a four-part serial dramatising the life of polar explorer Sir Ernest Shackleton.

October 1908. McMurdo Sound, Antarctica. Forced by ice conditions to break an agreement with Scott, Shackleton has returned to Ross Island. From the expedition's base at Cape Royds an attempt to reach the South Pole is about to begin. The logistical setback has severely limited their plans.

1914. Following the shattering news of Scott's death on his return journey from the South Pole, Shackleton formulates a new challenge on Antarctica. Sailing south in 'Endurance', his expedition will cross the vast continent.

December 1916. After the loss of 'Endurance', Shackleton and his 27 men endeavour to cross the frozen Weddell Sea. Land lies 350 miles away, and as they drift helplessly northwards they know that soon the ice will break beneath them.