In one of many poignant moments in David Diop’s third novel (his second translated into English), Michel Adanson, a dying French botanist, leaves his daughter, Aglaé, a notebook. The notebook is hidden; Aglaé will only find it — and in it, the most important story of her father’s life — if she goes looking for it. To receive her father’s secrets, Aglaé will have to accept his belongings days after his death in 1806. She will have to concern herself with a particular mahogany cabinet, and she will have to crack open its concealed compartment.

Adanson puts up these obstacles on purpose. “I fear your indifference,” he writes Aglaé in a final note. “If you are reading this, it is because you searched for my hidden life and you found it, because you cared about me a little.”

Thus begins “Beyond the Door of No Return,” a hypnotic, powerful historical novel in which stories nest within one another like dolls. There is the story of Adanson’s death and the story of the family he formed with Aglaé and her mother. And at the heart of it all, there is the story of what happened to Adanson when, at age 23, he traveled to Senegal, to a part of the country under the colonial control of his native France. “I made that voyage to Senegal to discover plants, and instead I encountered people,” his note to Aglaé explains.

We journey with him to the past. In Senegal, a young Adanson hears the tale of Maram Seck, the niece of a village chief and a “revenant” who — according to her uncle — was abducted three years earlier and sold into the slave trade. Maram eventually escaped to the peninsula of Cap Vert, returning “alive from beyond the seas, from that land where, for slaves, there is no return.” She has been hiding out there ever since, Adanson is told.

Yearning to learn the truth about Maram, Adanson sets out for Cap Vert. The journey, which takes place in 1752, is arduous. What Adanson uncovers there leaves him forever changed. He returns to France a haunted man.

The novel consists mainly of Adanson’s account of his time in Senegal, told in epistolary form. We leave Aglaé as a character when she starts reading her father’s letter, and find her again once she’s done and needs to cope with what she’s just learned.

Michel Adanson really existed — he was an 18th-century botanist, as well as a figure of the Siècle des Lumières, the Age of Enlightenment. In “Beyond the Door of No Return,” Diop expands on Adanson’s life, infusing it with a story of heartbreak to explain Adanson’s later obsessive work creating an exhaustive record of fauna and flora, to the detriment of his family life.

The titular door of no return, too, is real. It’s located on the island of Gorée, off the coast of Dakar, inside a building known as the House of Slaves. The house has become a powerful place of remembrance, a reminder of the human toll of the trans-Atlantic slave trade, which is the root of the tragedies in “Beyond the Door of No Return.”

Diop’s portrayal of Adanson navigating the effects and systems of slavery is sharp and astute. He’s disgusted by slavery, but his ability to travel (and find Maram) depends on his rocky rapport with the Senegal Concession, an organization “whose most important trade,” Adanson notes, is “that of slaves.” Because of his intellectual ideals and his dedication to science, he feels he’s separated from the racism and cruelty of his time, but he is never far from intentionally or unintentionally perpetuating harm himself.

In less skilled hands, the novel’s structure would not work. Diop — who in 2021 became the first French author to win the International Booker Prize, for his novel “At Night All Blood Is Black” — brings to life not only Adanson, but also the ways in which his dreams, loves and losses shaped the lives of those around him. It all coheres mesmerizingly.