but not always, linked in looser story arcs, which were noted in publicity materials but not in the titles. Timewyrm During a visit to Ancient Mesopotamia, the Doctor accidentally grants a cybernetically enhanced alien queen the ability to travel freely in time, thus creating the Timewyrm. The Doctor and Ace pursue the Timewyrm through time and space, from a Nazi-occupied Britain to the far future. Eventually, after a battle within his own mind, the Doctor is able to trap the Timewyrm in the body of a mindless baby, forcing it to relinquish its power and memories but giving it a new chance at life. Cat's Cradle The TARDIS is damaged by a three-way collision with an alien parasite and time explorers from ancient Gallifrey. While the TARDIS attempts to repair itself, the Doctor and Ace fight the sinister Butler Corporation in the early 21st century. The final repairs to the TARDIS's link to the Eye of Harmony require organic material, which the Doctor eventually acquires after a visit to Wales and Tír na n-Óg, a planet inhabited by beings modelled after figures from Celtic mythology and English folklore. However, unbeknownst to the Doctor, the organic material is tainted with a demonic intelligence, which infects the TARDIS. Future History Cycle On the planet Heaven, Ace falls in love with a Traveller named Jan. However, when Heaven is threatened by the deadly fungal Hoothi, the Doctor manipulates Jan into sacrificing himself to destroy the Hoothi. Furious, Ace leaves the Doctor's company, and he is joined by archaeologist Bernice Summerfield. Benny and the Doctor travel through the history of Earth and its colonies from the 22nd through 26th centuries, having adventures alongside Kadiatu Lethbridge-Stewart and William Blake. Both the TARDIS and the Doctor begin behaving more and more erratic as a result of the TARDIS's infection. As part of his plan to remove the infection, the Doctor brings Ace back on board the TARDIS, but she has spent three years fighting Daleks in Earth's Spacefleet, and has been somewhat hardened by the experience. Ace rejoins the Doctor, and turns the tables on him by manipulating him into a mission on the planet Lucifer. The Doctor continues to stage manage events like a chess master playing on multiple boards. At one point he even deposits Benny and Ace in 1909 and the distant future, respectively, to defeat an alien invasion on their own, while