Ever since Suranne Jones debuted as the formidable Dr Gemma Foster, she had the nation hooked. In fact, over 10 million people tuned in to watch the dramatic Doctor Foster finale. Now, almost two years later, the critically acclaimed dark drama is back – hitting screens for a second season this September. Giving us a sneak peek at the new series, the BBC has released a teasing trailer and there's already plenty of intrigue.