Agree with Wulf. Basic concept of a merman-castle is interesting. Why it got sunk in detail would be good. Why did they anger the gods? Are the inhabitants the cursed decendants of the original human inhabitants, not given 'proper' tailed forms like normal mermen (and as such, they would be shunned by the 'real' merman, who do not need artifical tails.) Go to Comment
There is a great idea here, somewhat reduced by the execution as AG mentioned.
It also suffers from requiring the targets be oblivious and for a number of coincidences to occur to work - he has to be injured while closest to the generals, not his servants, queen, cooks or others. Seems like quite the stretch.