in (one's) sights
1. In a position of being the target of one's planned attack. He has the CEO in his sights for his next big exposé.
2. Being the focus of one's attention and desire for possession or achievement. They've had an Olympic gold medal in their sights for the last eight years.
in (or within) your sights
within the scope of your ambitions or expectations. The image in this phrase and in raise your sights and set your sights on below is of a target visible through the sights of a gun.