The Beresfords investigate mysterious deaths at an old people's home.

Loosely based on "4.50 from Paddington" by Agatha Christie.

Prudence and Bélisaire Beresford have decided to take things easy. But when a rich Russian heiress disappears, Prudence can't resist and Bélisaire is forced onto the adventure. Their investigation will put them on the trail of a mysterious scientist who holds the secret to eternal youth...