The tell. From Wikipedia: a "tell' in poker is a subtle but detectable change in a player's behavior or demeanor that gives clues to that player's assessment of his hand. A player gains an advantage if he observes and understands the meaning of another player's tell, particularly if the tell is unconscious and reliable.

With Mary Higgins Clark, the unconscious and reliable tell is when her heroine is described as wearing her hair in a "chignon." From that point forward, despite the nefarious men in her life and the seeming possibility that the female lead might be culpable, your sympathies/concern are correctly placed on her behalf. Note: page 136 in "I'll Walk Alone;" page 54 in "The Shadow of Your Smile;" page 270 in "Where are We Now;" page 220 in "No Place Like Home;" page 362 in Daddy's Little Girl."

Higgins Clark does not repeat characters, but her strong leading women are almost interchangeable: brilliant lawyer, dedicated doctor, passionate marketer, etc. (Here, Zan is a talented interior designer.) Clark's plots are very linear: meet an amazing but troubled lady, see impending doom, run into a series of men of shady backgrounds and intents, someone is murdered, woman is in peril, pick which of the men will harm and which will help, love triumphs.

In a way, it is Mary Higgins Clark's very familiarity -- her tells -- which make her so relaxing a diversion. No heavy mental lifting nor gratuitous violence. Saturday morning cartoons and Nell conquering Snidely Whiplash with an assist from Dudley. Spending time with Mary Higgins Clark is like having high tea with a gentle, yet spunky maiden aunt. You don’t want to make a habit of it, but every time you go and she pours into her tea that little “strengthener” from the flask she keeps in her brocade handbag, you wonder why it is so long between visits.