Editor’s note: Francesca Serritella’s debut novel, “Ghosts of Harvard,” was released Tuesday. The Inquirer is publishing excerpts. This is the final installment..

A sound escaped from her mother’s mouth before she covered it with a tissue, which brought Cady’s attention back to her brother’s funeral. Her mother had never looked so stricken. Her face was wet with tears, her eyes bloodshot, and her cheeks were red like a fresh bruise, from rubbing or embarrassment. Cady had learned that the family of a suicide victim doesn’t get straight sympathy. Every “I’m sorry for your loss” that they received came with a look of veiled judgment, the unsaid “How could you let this happen?”

Cady longed to touch her mother, rub her back, do something to help, but she feared that any comfort she could offer would be so inadequate, she would only make things worse. Eric had been her mother’s favorite, but Cady understood — Eric was her favorite, too. When Cady didn’t get as much attention from her mother, Eric made up for it through his secret eye-rolls and exaggerated obliging smiles that he knew only she would catch. They were the co-conspirators, and their parents were the marks.

While Cady and her mother were still in shock, her father stepped up and took over the business of her brother’s death — notifying relatives, arrangements with the funeral home. But her mother was upset he’d chosen cremation, and Cady privately felt the same. There was a horror in imagining Eric being burned in some oven and pulverized, especially because it was so difficult for Cady to imagine him as a dead person.

Cady was in her bedroom above the kitchen when her father told her mother that the cremation had been done. She heard her mother banging pots and slamming cabinets and shouting, “How could you? Was that my punishment?” Cady couldn’t hear her father’s responses, but she could tell he’d remained calm, enraging her mother further. Cady normally took her father’s side when eavesdropping on their arguments, but not that night.

She imagined her father had set his jaw that evening much the way he was now, bottom lip pulled up and inward, creating craggy dimples on his chin. His temples had gone gray, and cold glints of silver shone throughout his dark hair. The skin on his neck lay slack against his collar, a bubble of blood where the razor nicked had dried to black. He was only fifty-six, but he was graying, aging, drying out. Whereas her mother’s grief rendered her preternaturally vivified, her father had turned to stone.

The rhythm of the preacher’s speech halted, and Cady looked up as he dropped his head. “Let us pray.”

Her mind returned to the praying mantis. After its cruel death, Eric produced his longest coded note, a plot for vengeance titled “Mission: Mantis Mommy Revenge.” The directions, translated, ordered her to cut open all of their old cat Bootie’s toys and empty the catnip into a Ziploc bag, then wait until three in the morning (she’d set her Shark watch alarm), sneak down to the basement to get the ladder, and take it to Jeremy’s house and climb on top of his garage. Cady never felt as nervous or important as she did that night. Sure enough, when she’d completed everything and reached the top rung of the ladder, there on the garage roof was Eric waiting for her. Cady remembered that he was pleased to see her, but not surprised — that was the best part about Eric, he always believed his little sister would come through.

Eric stood tall at the roof’s peak, silhouetted against the moonlight like a wolf on a mountaintop. He told her not to worry, he’d seen Jeremy sneak onto the roof plenty of times, but Cady was frozen. The cedar shingles were slick from a recent rainfall, and she watched him bend down and lift the last one beside the wall of the house. It revealed a hidden Ziploc whose contents looked identical to catnip. When Eric asked her if she knew what it was, she nodded so as not to disappoint him. He laughed and switched the bags.

He helped her join him at the top. Eric pointed out his bedroom on their home across the driveway. He said Bootie was sitting in the window, and positioned Cady in front of him so she could see, too. She strained to get taller on her tiptoes. Suddenly, the light went on in their parents’ room. Eric ducked down to hide, and Cady lost her balance.

She slid down the roof face-first, the shingles scraped past her outstretched arms. Just before she ran out of roof, a hand closed tight around her ankle and another yanked on the back of her shirt; Eric was grabbing her wherever he could catch hold, his feet scrambling to slow their slide. At last, he shoved his heels into the gutter. The pipe bowed under the force but held. He’d saved her.

Who would save her now? Cady looked at her parents, her inscrutable father, her trembling mother. Eric had always been the center of the family; when he was healthy, they were loving, celebrating, and planning for him, and when he became mentally ill, they were treating, arguing, and worrying over him. She felt they were floating away from one another, clinging to their memories of Eric like pieces of a sunken ship. She wanted to reach out to them, but to let go would be to drown.

Eric considered Mantis Mommy Revenge their greatest mission, because they got the pleasure of watching Jeremy pretend to get high on catnip for the rest of the summer. He’d retold the story to friends many times, but in every instance Cady had to add that Eric saved her life that night, and every time he shrugged it off. She could still hear him give his standard reply: “Would you have let me fall?”

But in the end, Cady hadn’t been there to stop him. She had let him fall. So had they all.

Excerpt from “Ghosts of Harvard, A Novel” by Francesca Serritella, copyright © 2020 by Francesca Serritella. Used by permission of Random House, an imprint of Random House Group, a division of Penguin Random House LLC. All rights reserved. No part of this excerpt may be reproduced or reprinted without permission in writing from the publisher.