When Nell Hudson is offered an opportunity to work alongside Sherlock Holmes, she turns it down. She has forged her own independent career, and is happy with things as they are. However, she has no choice but to reconsider when an anonymous bomber plants dynamite all over London and sends only Sherlock the clues to find it.
Soon, Nell’s and Sherlock’s lives are consumed as they race to defuse the devices and catch the villain as someone from Nell’s past reappears, seeking to wreck the new life she has built. But they are not the only one taking an unwelcome interest in her.
Someone else has tracked Nell down to Baker Street, and if they pay her a call, it will be fatal. Can Nell take back control of her life and help Sherlock stop the bomber before tragedy strikes?