Writing a biography of an artist requires a tricky balancing act between reviewing the life of the subject and reflecting on his craft.

In a genre slightly apart from this belongs “Her Husband” (Viking, $25.95), Diane Middlebrook’s survey of the marriage of American poet Sylvia Plath and her “bad boy” husband Ted Hughes, England’s former poet laureate.

What has previously been called Hughes’ “cruel streak” is referred to by Middlebrook as his “Neanderthal” tendencies, further compounded by his birth sign — Leo on the cusp — in her surprisingly new-age mystical and sociobiological approach to an often-told story.

It is a tale of talent, love and betrayal: Two robust scholar-artists at Cambridge experience desire, marriage, inspiration, publication and parenthood. Then come Hughes’ philandering and “desertion” and Plath’s suicide. Following are 35 years of Hughes’ questionable control of Plath’s manuscripts, including the reorganization of poems, “missing” journals, and a trove of Hughes’ documents locked away until 2023.

Such an entangled story might seem to preclude definitive statements, but Middlebrook wields a few wild ones in her attempt to explain the Hughes-Plath relationship, from their brief courtship to their 1956-63 marriage and to their “afterlife link.”

Middlebrook, who has taught literature at Stanford University, applies psychology (some babble), biology and astrology to define Hughes. She states that the male is fundamentally different from the female in his artistry. “Always thrumming beneath his powers of rational understanding and symbol-making is the zest of the sperm.”

She proposes that Hughes’ poetry, his persona and his sexual escapades can be explained within his larger desire to retain his animalistic essence. He longed to be a poet-shaman, she says, attuned always to the moans of the beasts. And his desire to pursue “the chase” above all else defined him. Middlebrook claims that these machismo leanings were formed in Hughes’ youth, particularly when he and his brother Gerald went on long hunting trips.

She writes: “He had once put the matter to Gerald in a kind of motto: ‘Energy is created by every activity that resembles the pursuit of quarry.”‘

Middlebrook suggests that Hughes left Plath partly because he disliked her “gooey” sentimentality and was intolerant of things that “boiled the wildness out of life and bottled it for consumption in irreproachable adjectives.” Middlebrook offers evidence from Plath’s letters: “wonderful husband,” “adorable children” and “lovely home.”

Middlebrook’s astrological defense is somewhat strained. “The night before Hughes’ marriage, a force impersonal and ancient is rising through water to fix its gaze on him. … Neptune in conjunction with the Sun at the midnight hour of his birth is beginning to express its influence in his life.”

In this story, Plath is the epic Pisces and Hughes the “Leonine persona” behind which his “self could crouch.” Even sympathetic readers may feel a little put off by the blanket statements and star charts offered as evidence.

Nevertheless, the book is a sultry and lavish affair with a few exceptionally strong chapters. It’s extremely easy to engage in, though Middlebrook appears suspiciously slow to condemn Hughes as an agent of his own infidelity or even to exalt him as complicated beyond these definitions.