Past perfect, future tense... Even angels need to chill out and Melanie's been looking forward to Lola's birthday beach party for weeks. So she's not impressed when Michael volunteers her and her angel mates for a medieval field trip. But when they get there, they stumble upon a time scam which could have serious repercussions for the Agency. They track the culprits back to their school in the twenty-third century - only to find that the kids are being monitored for sinister Opposition purposes. Can Mel change something which hasn't even happened yet? Angels must have their limits...