The story of one of the most important space exploration endeavours of this decade. Just as Gillen's enigmatic Master encourages Franciosi's Apprentice to seek out the key to life amidst a rugged alien landscape, ESA has been on a decade-long ambitious journey of its own, to unlock the mysteries of a comet and the origins of our Solar System with its Rosetta spacecraft, hundreds of millions of kilometres from Earth. Ambition complements the ongoing communication about Rosetta and adds a "human dimension" to the scientific and technological achievements of the mission, which include curiosity, drive and ambition.