Andrew MasonA year and a half after his board fired him from Groupon, Andrew Mason has invested $3 million of his own money in a new start-up venture – a comeback attempt that everyone in Silicon Valley is watching.

Mason launched Groupon in 2008 after two years of development. On the daily deals site, small businesses sell unused, off-hours capacity at a steep discount. These discounts appeal to deal seeking consumers, which, during the recession, were many. After just 16 months in business, the company was estimated to be worth over $1 billion dollars (http://www.forbes.com/sites/mashable/2011/01/07/the-history-of-groupon/).

By 2010, Mason was on top of the world. Groupon received a $6 billion dollar buyout from Google and Mason quickly (and famously) rejected it. Groupon had great momentum going into its initial public offering in 2011, but after that, things got rocky.

In 2013, after a string of quarterly losses and plummeting share prices, Mason was fired. When asked about the company’s troubles in an interview with Businessweek, Mason says he blames everything on himself. The biggest mistake, he says, was taking the company public too early.

After checking into a weight-loss camp, losing 30 pounds, spending a month traveling Southeast Asia with his wife, and moving from Chicago to San Francisco, Mason is back in the game. He is aiming to take the guided-tour industry by storm with his start-up Detour, which he is building into a central platform for GPS-based walking tours.

Inspired by a frustrating experience on a walking tour in Rome where he was forced to share a pair of earbuds with his wife, Detour’s technology allows people to synchronize tours on their separate phones. Mason is aiming to capitalize on people’s desire to have compelling experiences in their cities. Detour connects to the phone’s GPS to create intimate and immersive tours that are essentially audio short stories that you can walk through. Tours are narrated by a person with a special connection to that particular area, such as a local fisherman or Grateful Dead lyricist John Perry Barlow.

According to Businessweek, Detour began a limited testing period on July 30 with several walking and driving tours of the Bay area. Detour’s website says the app is coming in 2015, but allows users to sign up for early access.

Many have tried to redo classic tour guides as apps, but none have succeeded. Will Mason be the first? Stay tuned.