The Under Dogs by Hulbert Footner

"The pursuit by a super-woman detective, Madame Rosika Storey, of a strongly organized band of criminals whose speciality is jewel robbery on a gigantic scale. Rosika, in disguise, first has herself sent to prison, then is helped to escape by the organization, who thereupon accept her into their midst as a probationary, apprentice member. The directing genius of the group does not appear in person till the end, when Rosika traps him, but oversees from afar the undertakings of his 'operatives.' These latter he entrusts to the care of a fearful female Fagin who keeps house for them in a Greenwich Village den." —The Saturday Review