It's the final day of the regatta, and rival sailors Francine and Polly are neck-and-neck for the top spot. But just as the race gets under way, disaster strikes. Polly collapses and plunges into the sea, throwing the entire race into chaos. When it's discovered that Polly's smoothie had been tampered with, suspicion starts to grow. All eyes turn to Martha, the seemingly innocent smoothie maker, who now finds herself in the spotlight as an unlikely prime suspect. Martha and Humphrey, already juggling the demands of work and childcare, struggle to stay composed under this new pressure.