Time Rocks. Time Adventures Series, #5

Bradley Connors and James Garrett are back in London, this time on a fundraising trip for James' charity. After getting caught in a rainstorm outside their Soho hotel, they're once more transported back in time and find themselves in the middle of the London music scene of the 60s. When James gets mistaken for a well-known band frontman, a star-struck Bradley convinces his husband to stick around in the sixties long enough to help out the group by singing at a few of the group's upcoming concerts.
In the process, they get to live out Bradley's rock and roll fantasies, although James isn't quite as sure about the situation as his husband is. However, even though the pair thinks they have this time-traveling stuff down by that point, their adventure runs into a complication when James is recognized by someone he probably shouldn't be interacting with from a past that he's already abandoned. In the end, in order to get everyone back to their correct times before this time portal closes too, they will have to enlist the help of their friends on both sides of the time divide.