Two's a crowd

Mrs Hudson sold the flat, finally! And who should move in? Sherlock's counterpart:Celia Grant. She's a psychopath, acutely observant, a former cocaine addict & wishes she wasn't a writer. And she's wanted by both the Holmes brothers. John's busy with his daughter & Sherlock takes her on. But having someone as clever as you isn't good when you're a show off, and 3 people are jealous