Tick-Tock World

Tick-Tock World was a planet that the First Doctor, Susan Foreman, Barbara Wright and Ian Chesterton travelled on upon their adventures where they discovered that time was in a constant state of flux.

The Doctor suspected that it was located near or in Cleaver's Square, a galaxy "some considerable way" from Mutter's Spiral. He went on to further theorise that when space-time vessels passed near by the planet, its unusual properties caused them to malfunction and crash, though the ships' emergency landing protocols remained online long enough to eject their crew, while a normal spacecraft would pass by without issue.

Prior to the arrival of the Doctor and his friends, Nocta, Horl and Katta had all become stranded on the planet, the former surviving all the Xesto by hiding in a Zero Cabinet.

After leaving Carthage, the Doctor's TARDIS was drawn to the planet, making a violent crash landing. Upon meeting Horl and Katta, the TARDIS crew attempted to discover the Zero Cabinet only for the Doctor to be devoured by a Xesto. The nature of death on this world meant that he was trapped outside of time before he truly passed, meeting a woman who showed him to navigate the temporal fluctuations and monitor his companions.

Manifesting as an echo on the planet, the woman advised Susan on methods to try and escape but all failed and Susan was eventually left as the only survivor, fleeing to the Zero Cabinet to escape the Xesto. Realising that the woman was a future version of Susan, the Doctor encouraged his granddaughter to exploit the Blinovitch Limitation Effect, its effects amplified by the planet's properties. Sent back to the moment of the crash, both Susans advised the Doctor to redirect power from the TARDIS force field, providing enough power for the engines to break free of the planet. (AUDIO: Tick-Tock World)