Rose must survive the plague.

That is the objective her dying father gives twelve-year-old Rose and her brother, Lem, as he sends them away from their home. In the year 1665, London is overpopulated and still growing while a plague runs rampant through its households. Ever resourceful, Rose manages to find hope in new friends who help each other steal the essentials to survive the cruel streets of London.

But Rose also has something that may help them survive the plague. She has her father's last creation: a medicinal oil blend that could protect people against the sickness. As word about the orphan who possesses the secret to surviving the plague spreads to the city's network of thieves, the special oil becomes both a blessing and a curse.