Advice for Running 'The Lightless Beacon' for Call of Cthulhu 7e

The Lightless Beacon is one of the shorter and most accessible scenarios for first time Keepers, though I often take to expanding it slightly. As it stands, this is one of my favorite one-shot scenarios, and I have run it over a half-dozen times for various groups and never had a group not love it. Written to celebrate the game's 40th anniversary and available as a free download from Chaosium here! This scenario strands investigators on a desolate island with a failing lighthouse, missing crew and something...wrong!

It's design as a one hour convention game or one shot, but most groups I have run with end up closer to 2-3 hours. This also depends on a few alternatives to the written scenario that I prefer to build pacing and tension.

Scenario Overview:

• Title: The Lightless Beacon
• Setting: Beacon Island, off the Massachusetts coast ( I like to change this to any island near you if you live by the coast!)
• Runtime: 60–90 minutes (though many groups take 2–4 hours)
• Themes: Isolation, time pressure, unnatural transformation, deep sea dread
• Best For: 3–4 investigators, especially mixed-experience tables

The investigators are stranded by a failing boat during a rising storm. The island’s lighthouse has gone dark, and it soon becomes clear that the crew is either missing—or worse. Players must uncover the truth, restart the beacon, and survive long enough to escape.

What Works:

• Fast, Focused Setup – Players are thrown into danger quickly. No long exposition. Though if you want to build tension, I have a few suggestions for that in the next section.
• Rich Atmosphere – Lean into the fog, the storm, the isolation—this is your mood piece.
• Great for New Players – The pregenerated characters include built-in motivations. No Mythos knowledge required.
• Simple, Yet Open-Ended – Easy to expand into a longer session or tie into a larger campaign.

What to Watch For:

• Can Be Too Fast – Most players skip key locations unless gently nudged. I have found more than a few groups went straight to the lighthouse and missed half the island.
• Combat Can Escalate Too Quickly – If poorly timed, the horror climax can feel abrupt.
• Overcrowding Is a Problem – Don’t run this with more than four players—the lighthouse gets bottlenecked fast.

Keeper Tips & Tricks:

• Build Tension, Not Combat First: This scenario is about atmosphere. Let players find footprints, wreckage, or eerie silence before any threat appears. Don’t wall off tension behind rolls—offer clues freely and let them pull on the thread. Additionally, flip the map of the island upside down, have the Investigators arrive on the far side of the map and have to pass through the woods and passed the outbuildings to get to the Lighthouse, I do this every time and find it very effective.
• Don’t Start in the Storm: I like to start aboard the boat, meet each other, and spot the island before the weather turns. A rising storm adds urgency. Have the Investigators make Spot Hidden checks and see the flashes in the distance as the Lighthouse light is shattered.
• Keep one NPC Alive, Temporarily: I like to have one NPC still alive, I have done both Sam or the FBI agent, wounded and wandering the island in a blur. Or have him bleeding out in the workshed, either way, he dies shortly after the PCs arrive.
• Control the Ending Tempo: Make the final attack feel unavoidable and overwhelming. They can’t kill everything. Let the waves of creatures clearly multiply—it should feel like a choice between survival and sacrifice.
• If They Miss Key Clues, Move Them: Don’t punish players for exploring in “the wrong order.” If they miss something, just put it somewhere else. The flow matters more than the map.
• Use the Pre-generated Characters: The antique dealer and Bureau agent pregen characters have ties to the island. If you're using custom characters, make sure they have a reason to care about what’s happening.

Handout Design:

A couple of small handouts can dramatically improve immersion in this fast-paced game. Here’s how to enhance it with minimal prep.

1. Beacon Island Map - Provide a “safe” version of the island map without spoilers, this can be helpful to visualize for some players.
2. FBI Credentials and Fake Driver's License - I like my players to find the FBI agent's coat in the forest, with his fake name on a driver's license and his FBI credentials in the coat. This can be a bit of a red herring, but it builds tension
3. Journal: Providing a handwritten journal detailing George Cassidy's growing paranoia can be a great prop, and I find the handout from the PDF almost impossible to read. The text is written out below in case you find the same thing as me.

• February 13th, 1926 : I found something on one of my walks. A coin! I kept walking and found another then another! I know it's gold. Found some mechanical parts as well. Looks like it might be from a ship. Must have gone down recently, but I don't recall hearing anything about no wreck of late. Unless it went down in the last night's storm when the light was out. I better keep this quiet. Don't want the other two here to get a slice of the action. I will keep this journal as a means of documenting my findings. This has to be worth a mint!
• February 16th, 1926 : That coin catalogue I bought in Folly Point is useless. One thing I know is that the coins are old. Real old. I've asked if I can stay on for as long as I can until I'm sure there's nothing left there for me to line my pockets. And I have to find a good lead on these coins to go where the money takes me. Maybe I should write to some of my old "colleagues" to see if they can help. Should probably try some of those fancy antique stores in Rockport, while I'm at it.
• March 10th, 1926 : The coins are getting hard to find. The two new crew members aren't helping matters. Makes it difficult to search without being noticed. Hope they don't cause me any trouble. Even so, I've filled a small purse which I keep on me at all times.
• April 3rd, 1926 : I've got a good lead now. I'll be sending one more letter to Innsmouth then I'm confident I can get off this stinking island for good. I think Michael is watching me. I've bought a gun just in case.
• April 14th, 1936 : Smith said he will leave the lighthouse tomorrow morning. He says he doesn't care if it voids his contract—he's had enough of this island and everything on it. Least that's one less pair of eyes watching me. Still stuck with that sneak, Michael, though. Smith says the radio busted again halfway through talking to the bosses. Said he'd fix it before he leaves. Counted my coins just to be sure he didn't lift any off me in my sleep. I've seen Michael peering out the window, spying my daily walks. I'll have to be a bit more careful.
• April 12th, 1926 : Smith left without a word. Me and Michael didn't even see him go. Didn't take his paintings with him, which is a bit odd. Lousy rat didn't even repair the radio before he left. I'll get to it later tonight. Michael has gone to check something outside. Seems paranoid. Think there's more than just tobacco in that pipe of his. At least I get more time to write. No word from [the writing ends here on the handout]

Final Thoughts:

The Lightless Beacon is what Call of Cthulhu does best: it throws you into a terrible situation, gives you just enough tools to survive, and then lets you wonder what it cost you. It’s a great session for newcomers, and even better as a chilling prologue to deeper horrors.