The Doctor determines that the Adherents are responsible for the sabotage. However, they are robots commanded by Lady Cassandra. Cassandra admits to being the saboteur: her original plan was to create a hostage situation (with herself as one of the "victims") and profit from the compensation she would have gotten, but now intends to profit from the other guests' deaths, expecting her stock holdings in their competitors' companies to increase in value after they die. Cassandra teleports off the station as the spiders bring down the shielding on the entire station. The Doctor and the sentient tree Jabe travel to the bowels of Platform One to restore the automated shields, but it requires one of them to travel through several spinning fans. Jabe sacrifices herself to hold down a switch to slow down the fan blades. This allows the Doctor to reactivate the system just before the expanding Sun hits the station and destroys Earth.