The TARDIS crew have gone for some rest and relaxation at the Eye of Orion . However, things start to go awry as the Doctor's former selves are 'stolen' away: the First Doctor from a garden , the Second with the Brigadier at a UNIT reunion , and the Third with Bessie on the open road ; his Fourth persona is unfortunately caught in a time eddy when taken with Romana from Cambridge . Meanwhile, Sarah leaves home but is warned of danger by K9 ; she ignores it but is then captured herself whilst waiting for a bus .

The Doctors have been transferred to the Death Zone, a mysterious area containing the Tomb of Rassilon and closed off for millennia. The Second Doctor and the Brigadier escape from a Cyberman , whilst the Third rescues Sarah as she falls down a hill . The First Doctor and Susan find the TARDIS , whilst the Second Doctor realises where they are and he and the Brigadier head to the Tower .

Meanwhile, the High Council of the Time Lords have sent the Master into the Zone to assist the Doctors; he comes across the charred remains of another council member sent earlier . The Third Doctor explains the Zone to Sarah as they drive along, and are then stopped by the Master . However the Doctor doesn't believe him and as beams shoot from the sky they separate. Later, they are find they are being pursued by Cybermen .

Having realised thay they may part of the Game of Rassilon , the Second Doctor and the Brigadier enter the caves beneath the Tower . Meanwhile, the Fifth Doctor meets up with the Master, as the Cyberman attack he transmats back to the Capitol as the Master is knocked out . The Third Doctor and Sarah evade the deadly Raston Warrior Robot as it dispatches the Cybermen in pursuit and enter the Tower from above. The First Doctor heads to the Tower with Tegan and they enter through the main doors.

With the three Doctors having made their way through the Tower to the Tomb of Rassilon, they release the forcefield to enable the TARDIS to escape being blown up by Cybermen . They are then joined by the Fifth, whose mind has been overpowered by Barusa, whose claims of immortality are terminally granted by the ghost of Rassilon. With everything resolved, the Fourth is released from the eddy , and the Doctors go their separate ways ...