Of the Frank Packard books I have, The White Moll is unique in that the lead character and focus is that of a woman. Otherwise, it follows a similar formula of the other novels. It has about the most convoluted of all set-ups and backdrops of any of them though, which is saying something.
Miss Rhoda Gray was raised by her father, a mining engineer, down in South America. He gets ill and comes to New York to see a specialist. He's wealthy enough for the trip and treatment, but it doesn't leave alot left over for niceties and they settle in the poorest and crime-ridden section of town. Through an act of charity towards a crook she earns her nickname the "White Moll". "White" as being slang for being honest, trustworthy, and above board. "Moll" as that for a young woman (this is the first I've heard it used as being generic for a young woman and not one specifically a girl-friend to a crook or crook herself). When her father dies, she is left with just enough of a stipend to live on, but not to move or better her situation. She uses her money then to engage in acts of charity amongst crookdom. By these acts of kindness and known not to be be a stool pigeon or preacher, she earns the goodwill and protection of both crooks and cops.
Her life significantly changes when she comes across the old beggar woman Gypsy Nan close to death. Gypsy Nan refuses to be taken to a cop or hospital, at least not until taken first to her room at the flop house. In the candle-lit room, she reveals to Rhoda a small hiding place with clothes and loot, it turns out that Gypsy Nan is in reality a much younger woman! Shorn of her disguise as an old woman that would've exposed her at the hospital, they leave the flop house so that no link between her and Nan can be made. Then Rhoda is able to summon a cop and ambulance to take her to the hospital.
However, for Gypsy Nan it's too late and knowing she is dying, she manages to get a promise from Rhoda. She knows of an impending crime but she won't squeal on her mates. Instead she implores from Rhoda that she commit the robbery beforehand and then return the loot afterwards. Thus, forestalling the crime but not getting anyone arrested. Rhoda agrees and Gypsy Nan passes from this world.
Rhoda commits the act of robbery but is seen and pursued by the police. Only through the seeming innocent intervention of a good looking young man is she able to make her escape. With only a little lead, she finds herself near Nan's apartment. She enters and quickly dashes her clothes and loot in the hideaway and disguises herself as Gypsy Nan! Thus, Miss Rhoda Gray aka the White Moll becomes wanted by the police!
The next day, still in the Gypsy Nan disguise, she is visited by the good looking young man. He identifies himself as The Adventurer, a gentleman thief and he's looking for the White Moll in order to team up with her. However, their conversation is cut short as with his phenomenally good hearing he hears other feet on the stairs, Gypsy Nan gets a second visitor. The second is Parson Dangler, crook and gang-leader. More than that, he knows that Nan is a false identity as he's the husband to the dead woman that wore it earlier! However, through low lighting and subterfuge, Rhoda is able to keep secret that she's not the original woman. Through him, she learns that the gang's carefully laid plans had been forestalled often of late. Until last night, they had no clue as to whom, but now Dangler is sure it's the White Moll that's been the source of all their troubles! Thus, the White Moll is also wanted by the crooks!
That is the set-up. Rhoda Gray aka the White Moll is wanted by police and the crooks for a bunch of crimes she didn't commit and the one she technically did. She maintains the Gypsy Nan identity as both a safe haven and to gain information on future crimes that she then stymies in her compromised identity of the White Moll, all the while trying to find evidence that will clear her name. She also fights the growing attraction she feels for that self-professed crook The Adventurer whose path she continually crosses and matches wits against. And, with the deceased woman who was Gypsy Nan being secretly married to the crook who heads the gang that Gypsy Nan runs with, it's not that safe an identity.
The book is only disappointing in that despite the colorful name, the White Moll moniker is simply a nickname based on slang. It's not a separate identity, she doesn't wear all white and a mask. Also, despite her tomboy upbringings in the wilds of South America, Rhoda is not capable of being able to out-run, out-fight, or out-shoot a reasonably fit man. She only has her daring and wits. She's a colorful and sympathetic heroine, but she doesn't take those extra steps to make her fully a mystery-woman. With a female protagonist, Packard saddles her with more conflicts with her emotions, fears and doubts than he does his male heroes. However, it ultimately works in her favor. She suffers from much of the same emotions that most of us, man or woman, would feel in such situations, as unmanly as it would seem to acknowledge that in heroic fiction. Yet, it doesn't paralyze Rhoda to inaction. She feels those feelings, acknowledges them, then gets up and does what needs doing.
There's a thrilling car chase near the climax of the book, the only such scene in any of these books. Again, it takes a little reminding, that a car going 35-45 mph was really booking in those days (1919) and almost all cars were convertibles!