Sarah T. Hensleigh, née Parkes, is a palaeontologist and undercover Intelligence Convergance Group agent.
Before Ice Station Edit
Through unknown circumstances, Sarah Parkes joined the U.S. Army in the Chemical Weapons Division of the CDC. At some unknown point she was recruited into the Intelligence Convergance Group, who asked her to retire and take up palaeontology at university in order to find out what was going on with ice core research.
While doing research at Wilkes Ice Station, Sarah worked with Ben Austin to research sea snake venom. At the same time, she noted James Renshaw's discovery of atmosphere from three hundred million years ago, but disregarded it as unimportant to the ICG. During this time, she also met some of the scientists from the French ice station d'Urville, inclduing Luc Champion and Henri Rae, while also hearing other other French scientists such as Jacques Latissier.
When Renshaw hit metal in a 300 million year old drill core, and his supervisor Bernard Olson planned to write an article about it, Sarah knew she couldn't allow that to happen without the ICG knowing first. Upon hearing Renshaw arguing with Olson, Sarah decided to kill him, and used sea snake venom to ensure that he couldn't be revived. Because of their argument, Renshaw was accused of murdering him.
Subsequently, Sarah and the other scientists decided to investigate the source of the metal, and discovered it was in an underground cavern, and sent a team of divers down there. They reported that they had found what they thought to be an alien spacecraft, only for something to attack them. Sending out a distress signal, a group of French scientists from Dumont d'Urville came to assist, soon followed by a team of U.S. Marines. Sarah explained the Olson incident with their leader, Shane Schofield, claiming Renshaw had done it.
Soon, however, many of the French scientists were revealed to be soldiers, and had come to take the spacecraft. After the civilian quarters were compromised, Sarah, Kirsty, Abby Sinclair and Warren Conlon were forced to follow Book in order to escape death, but ended up being cornered. Before the French could open fire on them, an explosion caused by a gas leak destroyed the catwalk, causing Sarah and the others to fall into the diving pool. During their attempt to get out they were attacked by killer whales, and Sarah was unable to save Conlon.
In the aftermath of the battle, Sarah asked Schofield to allow her to join his team diving down to the cavern, claiming that it might be the result of either an alien culture or a super-ancient race of people; either way she wanted in, regardless of the danger. She gave Schofield her necklace to hold on to, not wanting to lose it.
Soon after arriving in the cavern with Gant, Montana and Santa Cruz, they spotted the sacecraft, Sarah taking the most interest in it and ignoring the bodies of the scientists who had come down earlier. Eventually she noticed that there was a kind of keypad on it, and after activating it they realised that there were numbers on it, meaning it was not an alien ship. Sarah decided to try and crack the code in order to try get inside the craft, but had much difficulty.
Soon Gant located the remains of an old ice station nearby, where they learnt that the craft had been built by one of the losing contenders in the bid to build the stealth fighter back in the 1970's, and the ice station had been lost in an earthquake. While looking over Silhouette's schematics, hoping to find another way inside, Sarah was told to go elsewhere by Montana, who was also ICG, while he killed Santa Cruz. However, before he could get Gant, a mutant elephant seal got him.
While hiding with Gant in a fissure from the seals, Schofield, Kirsty and Renshaw arrived, having being forced to escape the station because of the ICG's arriving SEAL forces. At this point Schofield had gotten a list of ICG personnel, and after seeing Sarah's maiden name on her necklace, realised she was ICG. Sarah proceeded to hold them all at gunpoint, and disbelieved Schofield's claim that a nuclear missile was inbound. Contacting the SEAL forces that were entering the station, Sarah was given permission to shoot them all if necessary. Admitting that she had killed Olson, she then explained why she had gotten involved with Brian in the first place. Before Sarah could kill Schofield, noting that she had kind of liked him, Gant shot her first, killing her.
- Hensleigh is the first female (human) antagonist to appear in any of Reilly's novels.