Complex sentence: It soon becomes a tale of mystery and intrigue, in which quite a lot of the characters are not what they seem, and Mitch Courtenay changes drastically from the person we first see.
Split into simpler sentences: It soon becomes a tale of mystery and intreague, in which quite a lot of the characters are not what they seem. And in which Mitch Courtenay changes drastically from the person we first see.