This week, Petter and Breki travel to a lighthouse in the beginning of the 20th Century and find that alongside the three custodians is a weird green blobby alien thing - but they don't encounter it until the very end, so it's all okay.
Show notes and links:
"Doctor Who" Horror of Fang Rock: Part One (TV Episode 1977) (imdb.com)
Horror of Fang Rock (TV story) - Tardis (wikia.com)
Horror of Fang Rock - Wikipedia, the free encyclopedia (wikipedia.org)
Max Headroom broadcast signal intrusion (wikipedia.org)