This one of the more enjoyable Hardy Boys books I've read. This one start off with the boys investigating an abandoned car at a local shop. The boys look for clues and quickly find a connection between the car and a slew of jewelry store holdups that their dad is working on. That is, by the way, one of the thing I like the least about these books- the two threads that invariably are related, in a way that strains credulity. These were, however, written to a formula, after all, so you just have to go with it.
They quickly find that a crooked arrow seems to be a promising lead. Their quest takes them into a rough part of town, and in the meantime their dad is shot- with a poisoned arrow! It's quickly discovered that the thieves are using cigarettes with a sleeping agent to knock out their victims.
In the meantime they fly to their cousin Ruth's ranch and find other clues that show a connection to the jewelry store holdups. Naturally the robberies and the disappearance are related! They arrive at Crowhead Ranch and it doesn't take them long to make enemies, as well as friends, and to suspect that someone at the ranch is a bad actor. The ranch hands are a colorful bunch, including Terry, a cowboy who burst into song whenever something interesting happens. After someone takes a shot at Frank with a arrow, they suspect it's poisoned and go to Santa Fe to have analyzed. After a bunkhouse brawl and a flash flood, they get another clue- the crooked arrow shows again. The story ends on a rousing note after a chase by dogs, a fire at the ranch and a posse. It's silly as usual how the gang operates in both locations but this one was fun.