Noted mystery author Max Allan Collins and artist Terry Beatty first introduced Ms. Tree to readers of Eclipse Magazine beginning in 1981, although the character also appeared in publications from Eclipse Comics, Aardvark-Vanaheim, Renegade Press, First Comics and DC Comics, through 1992.
Michael Tree was a private detective who took over her husband's investigation business after he was murdered, and in her first case, she captured the murderer and discovered his link to the Muerta organized crime family. Ms. Tree's dead husband was also named Michael, the joke being that after the marriage they each had the same name. Series creator/writer Max Allan Collins makes no secret of the fact that Ms. Tree was inspired by Velda, Mike Hammer's secretary, a stacked, gun carrying, six-foot tall brunette and Mike's lover, who was almost as tough as he was.
In addition to isolated cases, throughout the series, Ms. Tree's vendetta against the Muerta family was a major plot thread. Her methods often included deadly violence which she used with little hesitation. In contrast to typical genre conventions, she often faced serious consequences for these violent actions including arrest, imprisonment, commitment to a mental hospital, and involuntary medication.
In another genre divergence, the male Michael Tree's son, Mike (of course), inadvertently fell in love with the daughter of the Muerta Family matron. The female Michael disapproved of this arrangement but respected her stepson's decision. To her shock, when their relationship grew enough to make marriage probable, the Muerta family decided that Mike's stepmother was now family and initiated a reconciliation with her while going legit.
Michael was later impregnated by an old flame who was manipulating her to kill his wife. She decided to keep the baby, creating a unique series of adventures with her fighting off criminals even as she dealt with a full term pregnancy, while the mob family she hated moved to protect her in their own unique manner.
The Ms. Tree series frequently dealt with controversial political and sexual issues such as homophobia, abortion and bombing of abortion clinics, devil worship, child pornography, date rape and incest. One of the series' conceits, often alluded to in the narrative but never acknowledged explicitly in the comic books, was that Ms. Tree was the daughter of Dragnet protagonist Joe Friday. In Collins 2007 prose novel, 'Deadly Beloved' (the character's first appearance in 14 years), fans finally saw Michael Tree, pre-marriage, referred to as "Miss Friday".