Complex sentence: However, when Marlowe goes to meet Jones, Canino, a hired killer, attempts to find Agnes himself and then poisons Jones after being told of her location (which turns out to be false).
Split into simpler sentences: However, when Marlowe goes to meet Jones, a hired killer called Canino is there attempting to find Agnes himself. Jones is poisoned by Canino after disclosing her location (which turns out to be false).