The Adventure of the Accelerationist

While examining a collection of gems at a museum, Sherlock Holmes is startled something zips by him so quickly he can barely see it. When it pauses to smash a display case, the thing becomes briefly visible: a young woman, dressed outlandishly, with goggles protecting her eyes. Then she "speeds up" again and rockets out of the museum with Holmes in pursuit—but she easily outdistances him, leaving him gasping in astonishment. When Sherlock relates the bizarre event to his brother, Mycroft reveals that he has been tasked with discovering the truth behind recent reports of "augmented" humans: people with highly developed physical powers who have been aiding foreign agents. It's up to Sherlock to discover their strange secret.