This is part 11 of A Trivial Pursuit, a 25-part puzzle hunt. Each part is solvable on its own, with the exception of the meta-puzzle at the end.

Okay, let me tell you a story... I’ve got a terrible pest problem at home at the moment – a proper infestation – and so one afternoon last week I made my way out to that big mall that’s got pretty much everything you could ever want (you know the one – it’s been getting bigger and bigger for years). With well over a hundred different stores now, surely somebody there was bound to have what I needed...

I asked at the main desk and the receptionist helpfully directed me towards one of the two stores where she thought I could begin my search, but when I got there the store in question (whose company name was very vague indeed, I must say) was completely unstaffed. I enquired with the two neighbouring stores in the same row – one of which sold household appliances, and the other being some kind of currency exchange, I think – and they suggested I visit another store in an annexe to the main shopping precinct...

I arrived at the next store, only to find that this one also was deserted. I asked at the corporate recruitment agency next door (the one that provides secretaries for busy executives) but they just waved their hand at me and grunted dismissively. So I popped round to the other neighbouring store and was told my problem just wasn’t difficult enough for them to bother themselves with. They did at least recommend I should ask at the store two doors further along from them, so I did...

This next store specialised only in mirrors, and, thematically, everything inside – including their furnishings and even their logo – was back-to-front! Unfortunately, I think it was only open in the mornings, so it was shut. There was also a horrible stench in the air, and looking about me I soon realised that one of the neighbouring stores and the one opposite both sounded like they dealt in things that were especially smelly or disgusting. The other neighbouring store – albeit very small – was super helpful, and directed me back into the main shopping centre...

It was quite a walk to get to the next store, and – as my luck would have it – this one was also closed. I chatted to the Spanish storeholder on one side who seemed a bit dodgy really (stupidly so) but all he did was nod repeatedly – I wasn’t convinced he’d understood me at all. So I enquired at the store opposite and one of their neighbours, but together they both replied in the negative – they didn’t know when the store I’d needed would reopen. Meanwhile, the guy in the other store diagonally opposite said I should have come to them in the first place! Perhaps so, but it was a bit late for that now. However, he added, since I’d come so far already, it would probably be a good idea to pop my head in at the place right by the main entrance – the very first one you come to on entering the mall...

I retraced my steps to the entrance, and as I approached the place I’d been recommended, I stopped and shook my head in disbelief – it wasn’t a store at all, but a medical facility! It was also shut anyway, so I made my way back to the reception desk and stated plain all of the places I’d already traipsed around fruitlessly. “Ah, in that case,” she said, “there’s one store that you definitely should visit now – then I think you’ll be satisfied.” She drew me a map, so I followed it...

The route took me to a store SSW of the first one I had frequented. Upon arrival I tentatively peered through the glass frontage to find... a shop selling computer software. I slumped to the floor and wept. This attracted the attention of the neighbouring storeholders, one of whom described the whole situation as ‘concerning’, whilst the other tried his best to stay out of it and be invisible.

I left the mall empty-handed, but looking back on it now I can finally see – with the benefit of hindsight – that given what I was looking for, all of the folks I met had done their best to help me find it, and – in a way – I guess I kinda had.

What (specifically) was I attempting to purchase? The answer is 9 letters long. Please provide a floor plan of the mall and explain my route around it and the identities of the stores I visited along the way.

  • 5
    $\begingroup$ For the record, I think this - which is my 150th puzzle on PSE overall - is my personal favourite puzzle in the whole series. It may or may not be yours! :) $\endgroup$
    – Stiv
    Sep 25 at 13:54
  • 3
    $\begingroup$ I think your comment confirms the suspicion I had in terms of what the floor plan looks like ;) $\endgroup$ Sep 25 at 14:03
  • $\begingroup$ I went down the completely wrong rabbit hole of thinking your stores were the rot13(fgnpxrkpunatr fvgrf! ) i.stack.imgur.com/UYsvI.png $\endgroup$
    – JGibbers
    Sep 26 at 12:49

1 Answer 1


You were attempting to purchase:


And some explanation:

The big mall that does indeed (in some fashion) contain everything, is the Periodic Table as it contains every element. Although finding exactly what you need might be challenging.

The first (deserted) store has the very vague company name "Co" (Cobalt, 27), which sits between an appliance on one side - Fe (Iron, 26) and a US 5-cent coin on the other - Ni (Nickel, 28).

The annexe you visited next was the Actinides, where you stopped at "U" (Uranium, 92), which has Pa (Protactinium, 91) (which could be read as Personal Assistant) on one side and Np (Neptunium, 93) (No Problem, or possibly Non-deterministic Polynomial - of P vs NP fame) on the other.

Two doors further along is Am (Americium, 95) which has vertical symmetry in its abbreviation.
The unappealing neighbours in this case were Pooh! and Eww!, or Pu (Plutonium, 94) and Eu (Europium, 63).
The very small, but helpful neighbour was just a centimetre - Cm (Curium, 96).

Back inside the main store you went to P (Phosphorus, 15).
Their Spanish neighbour who just nodded could have said Sí (Silicon, 14). And the store opposite and their neighbour are N (Nitrogen, 7) and O (Oxygen, 8) who in combination said "No". The other diagonal neighbour was C (Carbon, 6), which would have been the other possible starting point that allowed you to visit the same sequence of letters.

Back at the main entrance, you found a common symbol for a hospital - H (Hydrogen, 1).

Then finally you found a seller of Operating Systems at Os (Osmium, 76) which has a "concerning" store in Re (Rhenium, 75) on one side and infra-red light in Ir (Iridium, 77) on the other.

enter image description here

So, in sequence you visited Co, U, Am, P, H, Os.

Which, with "Am" mirrored gives us Co U mA P H Os

  • 3
    $\begingroup$ This is correct, and you found most of the hidden references... The ones that got away are: rot13("vg’f orra trggvat ovttre naq ovttre sbe lrnef" = arj ryrzragf nqqrq bire gvzr; "tehagrq qvfzvffviryl" = Cnu!; "bayl bcra va gur zbeavatf" = n.z.; "n ovg qbqtl ernyyl (fghcvqyl fb)" = 'fvyyl pba') $\endgroup$
    – Stiv
    Sep 25 at 20:18

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