Complex sentence: In Angel's office, Wesley explains that Illyria rescued Gunn of her own accord, and Angel suspects that Illyria is hanging around Wolfram & Hart because she wants power.
Split into simpler sentences: In Angel's office, Wesley explains that Illyria left of her own accord, to go rescue Gunn. Angel also suspects that Illyria is still hanging around Wolfram & Hart because she wants power.