Complex sentence: Elle's fashion background helps her deduce that the prosecution's main witness-the pool boy-is lying about having an affair with Brooke, but when she shares this with Callahan, he dismisses it out of hand.
Split into simpler sentences: Elle's fashion background helps her deduce that the prosecution's main witness-the pool boy-is lying about having an affair with Brooke. When she shares this information with Callahan, he dismisses it out of hand.