A winter mystery for the longest nights.

Begin on the shortest day.

The Shortest Day is set on 21 December at Brackwater, a winter swimming club on the coast. For thirty years, Fran Ashby has led the solstice swim. This year, eleven people step into the lagoon at first light. At 08:21, her son calls for help beside the pontoon ladder.

It’s a complete case in four acts, free, for one or two players. You read the inquiry file, ask for the records it missed and tell Owen what really happened at that ladder. If you like a ritual, play it on the solstice itself. The case is set on that very morning.

Themes: drowning, deliberate harm and bereavement. No graphic imagery.

Plan the evening.

1. Pick your night. The solstice is the obvious choice. The quiet days between Christmas and New Year, when nobody is sure what day it is, may be better still.
2. Set the room for reading. Choose one screen you can both read without leaning. A lamp, or a candle if you enjoy the theatre of it, but keep enough light for the small print. Every record matters.
3. Make a flask. Tea, cocoa or something mulled. It’s a winter swimming club, after all.
4. Put the other phones away. The case lives on one screen. Everything else can wait.
5. Leave time for the ending. The best part is often the conversation afterwards: which clue changed your mind, and who was right first.

Start with the club chat.

Before the swim in The Shortest Day, the club is discussing the next morning. This exchange appears in the first act’s evidence.

Try it together. Read Fran’s reply aloud. Does it sound welcoming, stern or teasing? Each say which words gave you that impression. If you’re playing solo, try reading it in two different tones.

A character-reading exercise using two lines from the opening act. It gives away no answer to the mystery.

When one case isn’t enough.

The Shortest Day ends with a small thank-you towards your next case. If the evening has more in it, two longer investigations are waiting.

• When You Hear My Voice: an evening at Halcyon House, a voice over the speakers and a death nobody saw coming. 19 records, four acts, £9.99.
• Everything Went to Plan: a wet Norfolk night at the Marram Hotel, a robbery that went to plan, and a friend who had vanished by morning. 20 records, four acts, £9.99.

Each case is one payment for one or two players, with 12 months’ access. Progress saves in your browser, so a longer case can be spread across two winter evenings.

A mystery between Christmas and New Year.

Our cases aren’t Christmas stories, and they aren’t for the whole family. They’re written for adults, one or two at a screen, and they deal with grief, deception and death. That makes them a good fit for the evening after the visitors have gone home and the house is finally quiet.

If you’re hosting a bigger group, one person can read the records aloud while everyone else argues. It works, but nobody gets their own copy of the evidence. Better to know that before you plan the night around it.

Questions for a winter night in.