This time, it's not the TARDIS that dematerialises in the wrong place for a change, but a star cruiser that comes out of warp and crashes headlong into a scientific venture aboard the ominously named "Hecate". Their distress beacon is what brings our travellers to the rescue, and quickly they are embroiled in some intra-temporal shenanigans that release the "Mandrels" from another dimension onto tver mais...