18. Déjà Vu All Over Again

Complete story — includes the ending

Sherlock and Joan are handed a case of a woman who disappeared six months before. She had left behind only a video announcing that she was leaving her husband and reflecting on how her life was affected by the news of a woman who was given a bouquet and then shoved into the path of a subway train by a complete stranger. Sherlock thinks this case is ideal for Joan's first solo investigation. Meanwhile, he investigates the subway murder. Joan questions the husband of the disappeared woman; her instincts tell her he murdered his wife. Joan follows the husband and when she sees him load a large wooden trunk (which he claimed his wife took with her) into his car, breaks into it, but there is nothing inside it and Joan is arrested. After this failure and remarks from her friends, Joan starts doubting her decision to become a detective, but later she finds evidence that links both cases. Sherlock deduces the wife's video was made 18 months before, when another woman was killed in a subway. The husband had recreated the crime so he could claim the video had been sent six months before.