road bump in table top idea!

i've always wanted to DM a dnd game but for the LIFE OF ME i can not gget all the logistics of it down. So me and the usual DnD group have expressed interest in Vampire. I bought the world of darkness book which is a rule guide for vamp and white wolf. and were also using a friends vampire: the masquerade book. Thus begins my DMing WEEE

anyways, the usual monk guy wants to dm as well. so on alternating sundays we will take turns with his campaign in DnD and mine of vamp. I want to be not just another campaign so i'm mixing it up a bit. I love how we play Mafia on this board ( tho i dont like star wars enough!) so i want to do something simular with my campaign.

the setting: Neon City, Alaska ( bet you didnt know this was there Mae) Its a vegas style city somewhere near Juno. Sounds like it would bomb but it totally works cuz i said so. The whole so many days all dark thing attracts many vistors (how many months is it again?) It's a vampire run city with an entire underground structure and subway system.

players: 5, each player will be given a role to work into their story. at the very first session i plan on handing out pieces of paper with a note for each character telling them if they commited the murder or not.

Story: basically, a large vampire casino owner is killed when an explosion goes off in the subway underneath his casino. Every car on the train is crushed except for yours which happens to of been the last car. These 5 people are brought to the casino owners son as its suspicious that only they would come out unscathed. He knows someone set the explosion up and he wants to know who. As he's looking at the 5 of you, he realizes he's knows each of you for one reason or another. He gives hints and clues that he knows each of you have the perfect motive for killing off his father and ruining their casino. You have 24 hours to figure out who did it or everyone will be killed. Final note, the remainder of the casino is on lock down and none of you can leave. He leaves the clock begins.

Does that sound weak for a plot/storyline i'm kinda stuck on setting up clues now tho, but not everyone has turned in their characters. I have motives for 3 of the 5 people, no motive for the killer yet and i'm unsure how to go about not getting the killer foudn out immediatly.

this is my first time and its exciting and terrifying! hehe, i'd thought i'd share with you all and ask for help from the masters who think up our very fun mafia games and those who play them!