Simidele is a former human who has been transformed into a Mami Wata, a mermaid, by the orisa Yemoja. Her job is to collect the souls of people thrown overboard from slave ships to honor and bless them before sending them back to the supreme creator, Olodumare. But when a boy her age is thrown from a ship alive, Simi rescues him, in defiance of the laws forbidding her from interfering in the lives of humans. Simi and the boy, Adekola, need to plead their case before Olodumare, and in order to make contact with him they need two powerful obsidian rings. But both rings were given to Kola's younger siblings, Taiwo and Kehinde, in whom the twin orisas the Ibeji have manifested, and both children have been abducted.
The books in the series:
- Skin of the Sea (November 9, 2021)
- Soul of the Deep (September 27, 2022)
Skin of the Sea contains examples of:
- And I'm the Queen of Sheba: As Simi, Kola, Bem, Yinka, and Ifedayo travel by boat to Esu's island, Simi hears a noise in the hold, which Ifedayo thinks is a rat. When they investigate, they see one of the sacks moving and shaking. Yinka says, "If that's a rat, I'm the queen of the Mali Empire." It turns out to be Issa, a yumbo
boy who had previously acted as a guide for Kola and Simi, and stowed away on their boat so he could help rescue the twins. - Came Back Strong: In Skin of the Sea, Esu flings Kola into a wall, killing him. Taiwo, Kehinde, and Simi use the power of the obsidian rings to return his soul to his body and heal him. In Soul of the Deep, Kola learns that being resurrected has turned him into a brand new orisa, although he doesn't yet know the extent of his powers.
- Due to the Dead: In addition to the Mami Wata's work collecting souls, the orisa Olokun searches for bodies in the ocean to give them a proper burial under the seafloor.
- Giant Squid: The Omniran is a giant squid who was banished to the depths after hunting too many other creatures. Now he serves Olokun, who was also banished for creating tidal waves to kill humans. When the Mami Wata break Esu out of Olokun's prison, Olokun and the Omniran battle with them to try to stop them.
- Healing Factor: When Simi is in her mermaid form, she has a healing factor that can heal injuries in seconds.
- Magic Pants: Simi has pink and gold scales that cover most of her body. When she leaves the water and turns into a human, her scales turn into a wrapper.
- Meaningful Name: Simidele means "Follow me home," fitting her role as a psychopomp.
- Mokele-Mbembe: Appears in Soul of the Deep as a boat-destroying, man-eating monster that lives in the channel between the Oyo and Nupe kingdoms. According to legend, it sings every time it kills someone, and if it is ever killed, all the songs it ever sang will be released, creating one powerful song. Simi, Folasade, and Olokun kill it and harvest the soul song so Esu can use it to bind the ajogun.
- Morphic Resonance: Esu's island is guarded by a pack of bultungin, people who can turn into hyenas. In their human forms, their hair is in braids that resemble their hyena ears.
- My Significance Sense Is Tingling: While dining with the yumboes, Simi suddenly has a vision of a forest of black, rotten trees, littered with the corpses of livestock and yumboes, and a village of mutilated corpses. As she wakes up, she sees all the yumboes suddenly gasp in horror. Salif explains that the yumboes feel anything that upsets the balance of the earth. This turns out to be the abduction of Taiwo and Kehinde - the sudden absence of the Ibeji causes the forest and crops around Kola's village to die, although the villagers are still alive.
- A Taste of the Lash: When Simi rescues Kola, his back is covered in lash marks, which she treats with crushed wild lettuce.
- Tears of Joy: In Soul of the Deep, Simi is reunited with Ara, her best friend from before she became a Mami Wata, and they both cry.
- Title Drop: In the first book, Simi tells Kola, "When you peel back the skin of the sea, you never know what you will find."
- The Un-Smile: In Soul of the Deep, Folasade goes to check on Simi, who has spent the last six months living at the bottom of the ocean with Olokun. Simi, who has been very unhappy there, tries to smile at Folasade but instead only bares her teeth.
