Time Flight: The Doctor finally manages to deliver Tegan to Heathrow Airport, where he gets drawn into investigating the in-flight disappearance of a Concorde. Following the same flight path in another Concorde, with the TARDIS stowed in the hold, he discovers that it has been transported back millions of years into the past through a time corridor. Arc of Infinity: An antimatter creature has crossed into normal space via a phenomenon known as the Arc of Infinity but needs to bond physically with a Time Lord in order to remain stable. A traitor on Gallifrey has chosen the Doctor as the victim.