The following is a list of hostages in Cahills vs. Vespers.
- Fiske Cahill had been bathing, California, USA; when the Vespers captured him by releasing a baby water moccasin snake into the tub. He is a Madrigal.
- Status: Injured, shot in the shoulder, possibly recovered, escaped
- Reagan Holt was swimming in Puerto Rico when she was chased by a shark. She enters a shark cage, but the people on the boat were Vespers. She is a Tomas.
- Status: Injured, broken wrist, chest injury (trouble breathing), escaped
- Natalie Kabra had been shopping in London, England when she was captured by the Vespers by going into a soundproof box. She had thought it was a changing room. She was a Lucian. She was killed by trying to destroy the Doomsday device.
- Status: Escaped, Deceased
- Nellie Gomez had been eating a powdered jelly croissant in France that caused her to faint. She is not a Cahill by blood but has Madrigal status.
- Status: Injured, shot in the shoulder, bullet removed, bit by dogs. Possibly recovered, escaped.
- Alistair Oh was captured in an elevator in Tel Aviv, Israel while going to the optometrist. He was an Ekaterina.
- Status: Deceased
- Ted Starling was captured in an elevator in Tel Aviv, Israel while trying to find a cure for his blindness. He is an Ekaterina.
- Status: Injured, also blind, but not from Vesper activity, escaped
- Phoenix Wizard was captured at a Jonah Wizard concert in Tokyo, Japan while trying to find the 'hip-hop vibe.' He is a Janus.
- Status: Injured, gash on head, escaped
- Atticus Rosenbloom is kidnapped in A King's Ransom when running to Amy and Dan. He is a Guardian.
- Status: Escaped
Hostages in Day of Doom
- In an attempted photoshoot by the Vespers of the hostages, a lizard climbs onto Nellie's arm. Nellie uses it for the picture. The Attleboro Crew uses that lizard to find out where the hostages are. Evan found out that Sinead had been modifying the picture, revealing that Sinead is the Vesper Mole.
- Phoenix Wizard and Natalie Kabra removed the bullet in Nellie Gomez's arm.
- Fiske Cahill attempted to locate their Holding Cell and got a result of Mexico or Southern USA although he was proven wrong.
- Reagan Holt put the seven on a daily training regimen.
- After the seven ate their food one day, they noticed the casserole dish wasn't plastic, but ceramic, so they 'accidentally' dropped it on the floor outside their room in the facility with one big piece slipping under Ted's foot. Thus, they have obtained a weapon, though it wasn't mentioned again.
- The hostages broke the dumbwaiter.
- Attleboro thinks that the hostages are in Argentina. They were proven wrong in Shatterproof, the hostages are in Germany. But in Day of Doom, they are revealed to be in the Cascades.
- Ian Kabra suspects that the AidWorksWonders (AWW) (which his mother founded as a scam to get parole out of jail) and the Vespers are connected. The AWW headquarters is in Argentina.
- The Vespers send the Cahills a video of Nellie with a gun at her temple, she says "Hey kiddos." then the finger on the trigger twitches and the video cuts off. However, it is much more probable that it was merely an action to emphasize the threat of what would happen if Dan and Amy didn't give up the Madrigal ring (which is the most important part of the Doomsday Device).
- In Shatterproof , the hostages escape by pretending that Reagan is dead. They get captured again, but Phoenix fell off a cliff. Therfore he is presumed dead, however this was proven wrong in Day of Doom.