Latchkeys — Paul Kupperberg

When the Latchkeys travel back to 1920s New York and discover they're in an Irish speakeasy that will someday become Mercy and Marguerite's parents' restaurant, they're thrilled. But the initial fun fades as they're confronted with feuding Irish brothers, dirty cops, dirtier Prohibition agents, and a wily Splinter that doesn't want to be found. Plus they need to make sure they don't damage the bar in the past, lest they change the twins' future!