Eight colleagues H, I, J, K, L, M, N, and O are seated around an octagonal…

Concept: In a circular/polygonal seating puzzle, first convert every relative clue ("neighbour of", "immediately next to", "between") into a block of consecutively seated people, then use directional clues ("second left of") -- always read in the SAME rotational direction throughout the puzzle -- to place the remaining people and close the loop. An arrangement is confirmed only when every clue, including at least one not needed for the initial placement, holds simultaneously.

Application:

1. I is the neighbour of both M and N, so M and N sit on either side of I -- this fixes the block M-I-N.

2. J is immediately next to M, and M's other neighbour is already I, so J must take M's free side -- this extends the block to J-M-I-N.

3. L sits between J and H, meaning L is adjacent to both J and H. J's free side (its other neighbour, M, is already fixed) is where L attaches; H then attaches to L's outer side -- this extends the block to H-L-J-M-I-N, fixing six of the eight seats in order.

4. Only two seats remain, between N and H, for K and O. Reading "second left" in the same rotational direction used to build the block, O is the second person to the left of N -- so one person sits immediately after N, and O sits immediately after that person, right before H.

5. Applying that placement: the person immediately after N is K, then O follows K, then H closes the loop -- giving the full order H-L-J-M-I-N-K-O around the table.

Cross-check: Test this against the one clue not yet used for placement -- "H is the second left of K." Counting two seats in the same rotational direction from K (K → O → H) lands exactly on H, matching the clue independently and confirming the arrangement without contradiction.

Result: The finished order around the table is H, L, J, M, I, N, K, O. The person sitting directly between O and N is K.