On what should have been a routine mission to the star system of 61 Cygni A, Delia Kemp finds herself shunted thousands of light years into uncharted space. The only survivor of a catastrophic starship blow-out, Delia manages to land her life-raft on the inhospitable, ice-bound world of Valinda, and is captured by a race of hostile aliens, the Skelt.

As the long winter comes to an end and the short, blistering summer approaches, the Skelt will stop at nothing to obtain Delia's technical knowledge – but what Delia wants is impossible: to leave Valinda and return to Earth.