The Castaways by Elin Hilderbrand Summary: Secrets and Scandals in Paradise

Last Updated: September 4, 2026

Nantucket’s Most Heartbreaking Summer Unraveled

Imagine a circle of eight friends so tight that two decades of shared vacations, child-rearing, and secrets have fused them into a single organism.

Now imagine that organism losing two of its limbs overnight.

That is the world Elin Hilderbrand builds in The Castaways — a Nantucket novel where grief does not simply arrive and depart.

It settles in, rearranges the furniture, and starts opening locked drawers.

The novel sits at the crossroads of contemporary fiction, mystery, and women’s fiction, but its true pulse is the quiet suspense of watching people discover they never really knew each other at all.

Hilderbrand sets the tragedy against Nantucket’s cobblestone charm and summer glamour, creating a backdrop where the island’s beauty makes the unraveling feel sharper.

No one is innocent here.

That is not a judgment — it is simply what the story reveals.

👉 On YouTube: The Castaways Book Summary by Elin Hilderbrand

TL;DR: One Couple Lost, Six Lives Unmade

The MacAvoys — Greg, a charismatic music teacher, and Tess, a gentle kindergarten teacher — sail out on their twelfth anniversary and never return.

Police Chief Ed Kapenash, himself part of the friend group, investigates what looks like a tragic accident.

But toxicology reports and phone records pull a thread that unravels a secret six-month affair between Tess and Addison Wheeler, a pill given in jealousy by Addison’s wife Phoebe, and a final betrayal Greg committed the night before he died.

The remaining friends must decide whether the truth will destroy what is left or become the foundation for something new.

Find more book summaries of Elin Hilderbrand’s novels at URSummary’s Elin Hilderbrand collection.

Characters In This Book

Character	Role
Ed Kapenash	Nantucket Police Chief and Greg’s close friend who leads the investigation into the drowning.
Andrea Kapenash	Ed’s wife and Tess’s cousin, a former champion swimmer who defined herself by protecting Tess.
Greg MacAvoy	A talented musician and teacher whose reckless choices and infidelity ripple through the entire group.
Tess MacAvoy	A devoted mother and teacher caught between loyalty to her husband and passion for her lover.
Addison Wheeler	A wealthy real estate magnate who carried on a secret affair with Tess and is named executor of her will.
Phoebe Wheeler	Addison’s wife, traumatized by 9/11 and dependent on prescription drugs, who gives Tess a dangerous pill out of jealousy.
Jeffrey Drake	A steady farmer and Andrea’s former lover who becomes her anchor during mourning.
Delilah Drake	Jeffrey’s wife, a free spirit who secretly loved Greg and witnessed his final betrayal without speaking up.
Chloe and Finn MacAvoy	The seven-year-old twins orphaned by the drowning, raised collectively by the surviving friends.
April Peck	Greg’s former student whose appearance at the funeral forces hidden truths into the open.

The Castaways Summary Elin Hilderbrand (1)

The Castaways Summary: A Deep Dive Into the Tragedy

SPOILERS AHEAD. This section recounts the full story, including the ending.

The novel opens with Police Chief Ed Kapenash receiving the call. Greg and Tess MacAvoy are missing at sea.

Greg, overconfident in rough weather, took a larger sailboat than he could handle into thirty-mile-per-hour gusts. The Coast Guard finds their bodies. The cause appears to be drowning.

But Ed notices things that do not sit right. Tess’s toxicology screen shows a powerful illegal opiate in her system. Her phone records list five calls from Addison Wheeler on the morning she died.

Addison has already taken possession of Tess’s cell phone, quietly hiding evidence.

The narrative moves backward and forward through time. Readers learn that Tess and Addison began a passionate affair six months earlier during a group ski trip to Stowe, Vermont.

Addison wanted Tess to leave Greg. Tess hesitated because of her young twins, Chloe and Finn.

Phoebe Wheeler discovered the affair. Consumed by jealousy and numbed by her own long-term drug dependency, she gave Tess a “Number Nine” pill before the anniversary sail. Her intent was to ruin the day. She did not anticipate that the drug would impair Tess’s ability to survive a capsize.

Greg had his own secrets. Recently cleared of a sexual misconduct allegation involving a student named April Peck, he met April at Cisco Beach the night before he died. Delilah Drake saw them together. She told no one — not Tess, not her husband Jeffrey.

That silence gnaws at her after the drowning.

The funeral becomes a pressure cooker. April Peck appears uninvited. Andrea Kapenash, Tess’s cousin, spirals into a grief so consuming that the group struggles to hold her together. Addison withdraws into guilt. Delilah grows paranoid and reckless.

The investigation tightens. Ed pieces together the toxicology, the phone calls, and the witness accounts. He confronts Addison about the affair. He learns about the pill from Phoebe. He discovers that Tess wrote a final note choosing Greg over Addison — a note Addison found too late.

Delilah reaches her breaking point. She impulsively takes her own sons and the MacAvoy twins off the island, driving toward New York in what nearly becomes a kidnapping. She eventually turns back, accepting that escape solves nothing.

The friends gather for a formal reckoning at the Drakes’ house. Each confession comes out: the affair, the pill, the witnessed betrayal, the stolen phone. Ed declares the deaths an accident, noting evidence that Greg and Tess died trying to save each other in the water.

One year later, the group remains together. They are raising the twins as a collective family. Phoebe, now recovered from her addiction, has a new baby named Reed Gregory.

The Castaways dedicate a nature trail to Greg and Tess and walk it together — bruised, reshaped, but still standing.

Summary by Chapter: Smart Grouping

SPOILERS THROUGHOUT.

The Shattering Impact

The novel opens with the immediate shock of the drowning.

Chief Ed Kapenash identifies the bodies and breaks the news to his wife Andrea, who collapses into what the book calls a “psychotic” grief. Each couple reacts with a mixture of horror and private dread about what an investigation might reveal.

The History of the Castaways

Flashbacks — especially to a group trip to Las Vegas in 2000 — establish how the four couples formed their identity. The social hierarchy solidifies. Early cracks appear in the Drake and MacAvoy marriages.

Greg’s flirtatious nature surfaces in ways the group learned to overlook.

The Public Grieving and Private Doubt

The funeral draws the entire island, but April Peck’s presence agitates the group.

While Nantucket mourns two beloved teachers, Ed quietly investigates the toxicology report. Addison secretly holds Tess’s phone, deleting evidence of their affair.

The Revelation of the Affair

Addison’s perspective reveals the full history of his relationship with Tess, beginning in Stowe.

Meanwhile, Andrea and Jeffrey begin meeting secretly in a hot farm attic, recounting every detail of Tess’s life as a form of therapy. They eventually piece together that Tess had a secret lover.

Confessions and the Breaking Point

Phoebe realizes the pill she gave Tess contributed to the drowning. Addison discovers Tess’s final note choosing Greg.

Delilah, crushed by guilt over witnessing Greg with April, flees the island with the children, forcing the group to confront how close everything is to collapsing entirely.

Reckoning and Moving On

The friends assemble to reveal every hidden truth in a single, painful meeting.

They choose forgiveness. The epilogue jumps forward one year, showing the group raising the twins together and dedicating a memorial trail to Greg and Tess.

Beneath the Surface: What Drives The Castaways

Theme	How the Book Presents It
Grief and Loss	Each character grieves differently — Andrea collapses, Addison numbs himself, Delilah acts out — showing how the same death fractures people along their existing fault lines.
Secrets and Infidelity	The affair between Tess and Addison, Greg’s encounter with April, and Delilah’s hidden love for Greg form a web of betrayals that predate the drowning.
The Fragility of Friendship	The Castaways’ two-decade bond nearly shatters when tested by death, revealing that shared history does not equal honest connection.
Guilt and Redemption	Phoebe’s guilt over the pill and Delilah’s guilt over her silence drive them toward self-destruction before both find paths to atonement.
Public Persona vs. Private Truth	Greg and Tess were beloved teachers with a seemingly perfect marriage; every character maintains a facade that the investigation strips away.
Parental Duty vs. Personal Desire	Tess’s conflict between leaving Greg for Addison and staying for her children sits at the heart of the tragedy.

The Castaways Summary Elin Hilderbrand (3)

Frequently Asked Questions

What is The Castaways by Elin Hilderbrand about?

The Castaways follows four Nantucket couples whose lives unravel after Greg and Tess MacAvoy drown during an anniversary sail, exposing secret affairs, drug use, and betrayals among the surviving six friends.

Does The Castaways have a happy ending?

The book ends on a note of cautious hope — the friends confess all their secrets, choose to forgive one another, and commit to raising Greg and Tess’s twins together, with a one-year epilogue showing their rebuilt lives.

Who gave Tess the pill in The Castaways?

Phoebe Wheeler gave Tess a “Number Nine” pill before the anniversary sail out of jealousy after discovering Tess’s affair with her husband Addison, unknowingly contributing to Tess’s inability to survive the capsize.

Did Greg cheat on Tess in The Castaways?

Yes, Greg MacAvoy met with his former student April Peck at Cisco Beach the night before he died, and Delilah Drake witnessed the encounter but chose not to tell Tess.

Is The Castaways part of a series?

The Castaways is the second book in Elin Hilderbrand’s four-book Nantucket series, though each novel can be read as a standalone story with its own set of characters and resolution.

What happens to the twins in The Castaways?

Chloe and Finn MacAvoy, the seven-year-old twins orphaned by the drowning, are raised collectively by the six surviving friends, who commit to keeping the children together on Nantucket.

Where is The Castaways set?

The novel is set on Nantucket Island, with the story moving between the island’s beaches, harbors, and historic neighborhoods, contrasting its summer beauty with the darkness of the central tragedy.

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