Lunar Module 32, commanded by Steve Maddox, departs from the
Moon bound for Earth; its radar picks up an unidentified object shortly before
re-entry. The audience sees that this is a small alien
limpet-like
UFO, hiding in the
Apollo 8 space wreck, which attaches to the passing LM 32 and interrupts communications with the SHADO Moonbase and modifies the
spaceplane's course, causing the Lunar Module to re-enter the atmosphere at too steep an angle. The limpet UFO detaches from the stricken spacecraft, which explodes shortly after, and returns to its hiding place to await another victim. Meanwhile, Straker is trying to convince General Henderson, head of the International Astrophysical Commission, to increase debris-eliminating space missions as he thinks that his pilots risk more in a month than Henderson's do in a year. Henderson mockingly accepts this but insists on activating the "Washington Square" protocol: the cancellation of all lunar
spaceflights. After Maddox's
burial-in-space funeral at the Moonbase Paul Foster, convinced that it was not human error that killed his friend, blasts off in a lunar module against orders and flies on the same course to prove Maddox's innocence. As with LM 32, the limpet UFO attaches itself to Foster's module and interferes with the controls, proving his theory. Foster survives by deliberately entering the atmosphere at a very shallow angle which prevents the limpet UFO from steepening his spacecraft's descent enough to destroy it before it detaches and returns to hiding. Straker issues orders to destroy all space wrecks where the UFO might be located and invites Henderson to SHADO Control, having deduced that the limpet craft was some sort of lure. In response a standard UFO prepares to attack the Harlington-Straker Studios but is soon destroyed by
Sky One. Henderson is convinced of the merits of Straker's request to clear all space debris and agrees to support the plan but cautions Straker that, like himself, he may also have been too sure about being right. ==Regular cast==