He kept a diary of the adventure that happened around him. The Fifth Doctor kept it in his TARDIS and had read most of it to Turlough. After meeting the Doctor, Haliwell seemed to fall in with him quickly and allowed the Time Lord to help with their investigation of the moon. They were chased by all manner of creatures until they were saved by Captain Sinclair.
Haliwell was slightly attracted to the Professor's daughter, Emily Boyes-Dennison. They got along well after they had been captured by the Warden in the Citadel. They met one of the creatures who could not speak English, but many other languages. They were held prisoner in the vast place.
He and Emily were tested using experiments such as a running corridor, where they would escape an electrified wall. In a later test, they were forced to choose weapons for a fight. Haliwell chose a large cutlass and a small axe. In an artificial forest they met teeth and sword with all manner of creatures. Their last enemy was a Hydra, which he managed to defeat using his cutlass and blinding the creature's three eyes. He treated Emily's wounds using an alien solution. He continued to write his experiences in his diary.
They were then confronted by two robotic hunters. One he managed to slash to bits with his sword and the other was crushed underneath a saucer which Turlough had flown. Emily was keen to fly one of them to his dismay and worry, but he gave in.